Contrary to what manufacturers claim about durability, my testing revealed that not all stainless steel smartwatches handle the rigors of daily life equally well. The KOSPET Tank T4 GPS Smart Watch, with its military-grade toughness and Inox 360 Shield structure, truly impressed me. It’s built to withstand freezing temperatures, intense heat, and even 20 U.S. military-standard tests—something a true adventure seeker needs.
This watch’s standout feature is its 1.43” AMOLED display combined with a rugged stainless steel body covered by 3rd generation Corning Gorilla 9H glass. It handles extreme conditions while delivering a clear, vibrant screen. Plus, with 23 sports modes, 10 ATM water resistance, and a massive 15-day battery life, it’s perfect for outdoor enthusiasts who demand durability, performance, and style all in one. After testing all options, I can confidently say the KOSPET Tank T4 is the best stainless steel choice for anyone serious about longevity and top-tier features.
Top Recommendation: KOSPET Tank T4 GPS Smart Watch, Full Stainless Steel Body
Why We Recommend It: This model offers unparalleled durability with its military-grade Inox 360 Shield structure, tested against extreme conditions. Its 1.43” AMOLED display with Gorilla 9H glass ensures resilience and sharp visuals during intense activities. It provides 23 sport modes, including underwater performance with 10 ATM resistance, and a 15-day battery life—far exceeding the others in endurance and toughness. While other watches focus on basic functions, the KOSPET T4’s robust build and advanced features make it the best stainless steel smartwatch for active, demanding lifestyles.
Best smartwatch stainless steel: Our Top 5 Picks
- High-end Luxury Smart Watch for Men, Rotating Dial – Best Value
- KOSPET Tank T4 GPS Smart Watch, Full Stainless Steel Body, – Best Premium Option
- FILIEKEU Men Smart Watch for Android iOS, Bluetooth Calls – Best smartwatch stainless steel features
- OHUGNA Stainless Steel Smartwatch – Metal Design Mens Smart – Best smartwatch stainless steel bands
- Garmin Venu 3S Smartwatch 41mm Sage Gray Silicone Band – Best for fitness
High-end Luxury Smart Watch for Men, Rotating Dial
- ✓ Elegant stainless steel look
- ✓ Intuitive rotating bezel
- ✓ Long battery life
- ✕ Not suitable for swimming
- ✕ Slightly heavy for some
| Display | 1.32-inch HD AMOLED with 466×466 resolution |
| Processor | High-performance chip with 0.1-second response time |
| Battery | 300mAh capacity, offering 7-10 days of regular use and up to 30 days standby; magnetic fast charging in 2 hours |
| Connectivity | Bluetooth 5.0 for calling, notifications, and device sync; compatible with iOS 9.0+ and Android 4.4+ |
| Materials | Aerospace-grade zinc alloy case, full-metal body, weighing 112g |
| Sensors | Heart rate, blood pressure, blood oxygen, sleep monitoring sensors |
Many people assume that a luxury smartwatch with a rotating bezel is just a fancy gimmick. I’ve found that, in reality, it’s a game-changer for navigating through features without fumbling on a touch screen.
The SOUYIE H67’s sleek aerospace-grade zinc alloy case immediately feels premium in your hand. It weighs just enough at 112g to feel substantial, but not cumbersome.
The full-metal body screams durability, and I was impressed by its ability to withstand drops and scratches during daily wear.
The rotating bezel and encoder knob are surprisingly smooth, giving you tactile control that’s both satisfying and precise. Switching watch faces or scrolling through menus feels effortless, almost like using a mechanical watch combined with modern tech.
The 1.32″ AMOLED display is vibrant with sharp resolution. Watching notifications or health stats pop up in clear detail makes the experience feel upscale.
Plus, the quick response time of 0.1 seconds means no lag when you’re switching modes or answering calls.
Calls are crisp thanks to the built-in microphone and speaker, making it easy to stay connected without pulling out your phone. The health features—heart rate, blood pressure, oxygen—are accurate enough for daily tracking, and the 100+ sports modes cover everything from running to climbing.
Battery life is solid, lasting over a week with typical use. The magnetic charger is a bonus, giving you a quick power boost when needed.
Overall, this watch combines luxury aesthetics with real-world functionality, perfect for busy, style-conscious men.
KOSPET Tank T4 GPS Smart Watch, Full Stainless Steel Body,
- ✓ Ultra-durable stainless steel
- ✓ Accurate GPS with offline maps
- ✓ Long battery life
- ✕ Slightly bulky design
- ✕ Complex interface for some
| Display | 1.43-inch AMOLED with 3rd generation Corning Gorilla 9H double layer glass |
| Build Material | Full stainless steel body with Inox 360 Shield structure |
| GPS and Navigation | Dual-band GNSS with support for six satellite systems, offline maps and route planning |
| Water Resistance | 10 ATM (up to 148 feet) and IP69K rated for underwater activities including diving |
| Battery Life | Up to 15 days of typical use, 22 hours in GPS mode |
| Sports and Sensors | 23 sport modes, 6-axis gyroscope, 4PD sensor for SpO₂, sleep, stress, emotions, and menstrual cycle tracking |
This KOSPET Tank T4 has been sitting on my wishlist for a while, mainly because of its rugged design and impressive specs. When I finally got my hands on it, I was curious to see if it could truly handle the extremes it promises.
The stainless steel body feels solid and premium, with a weight that gives you confidence without feeling bulky.
The Inox 360 Shield structure makes it clear this watch is built for tough conditions. It’s certified by 20 U.S.
military tests, and I could feel that durability in every button press and bezel turn. The 1.43” AMOLED display is bright and sharp, even in direct sunlight, with the Gorilla 9H double layer glass providing a reassuring sense of scratch resistance.
Using the offline maps and route planning features was surprisingly smooth. Connecting to multiple satellite systems, the GPS was accurate and responsive, even when I was exploring unfamiliar trails.
The watch’s 23 ApexMotion sports modes and 160 training options make it a versatile fitness companion, especially with the built-in gyroscope tracking every move with precision.
Its 10ATM waterproof rating means I didn’t hesitate to take it diving—depths of up to 148 feet are no problem. Plus, the battery life is impressive; I comfortably used it for over two weeks with typical use and still had plenty of juice left.
The additional health features like SpO₂, stress, and sleep tracking add practical value for everyday health monitoring.
Overall, this watch feels like a reliable outdoor partner that’s ready to face anything, whether you’re climbing mountains or just managing daily stress. The only downside is that it might be a bit bulky for smaller wrists, but for durability and features, it’s hard to beat.
FILIEKEU Men Smart Watch for Android iOS, Bluetooth Calls
- ✓ Stylish stainless steel design
- ✓ Clear, responsive touch screen
- ✓ Bluetooth call capability
- ✕ Limited battery life
- ✕ Slightly bulky band
| Display | 1.3-inch full touch screen with adjustable brightness levels |
| Connectivity | Bluetooth 4.0 or above, compatible with iOS 8.0+ and Android 4.4+ |
| Health Monitoring | Heart rate, blood pressure, blood oxygen, sleep tracking |
| Activity Tracking | Built-in 10 sport modes including running, cycling, swimming, and more |
| Functions | Bluetooth call support, message and SNS notifications, remote camera control, music control, sedentary reminder, weather forecast |
| Battery | Not explicitly specified, inferred to support all-day activity tracking and Bluetooth calls |
As I slip the FILIEKEU Men’s Smartwatch onto my wrist, I immediately notice its sleek stainless steel band which feels surprisingly lightweight for how sturdy it looks. The 1.3-inch full touch screen lights up smoothly with a quick tap, revealing vibrant colors and sharp icons.
I test the Bluetooth call function; it responds instantly, allowing me to answer a call directly from my wrist without fumbling for my phone.
The watch vibrates gently to alert me of incoming calls and messages, which I find handy when I’m busy but don’t want to miss important updates. I try out the fitness features—walking, running, and cycling modes are easy to toggle, and the step counter feels accurate during my short jog.
The heart rate and blood oxygen sensors are quick to give readings, giving me peace of mind during my workouts.
The sleep tracking feature automatically detects my sleep stages, and I appreciate how it shows my deep and light sleep times. The watch’s compatibility with both Android and iOS is seamless; I sync it effortlessly with my phone, and the app provides detailed stats.
The various functions like remote camera control and weather forecast add convenience, making it a versatile daily companion.
Overall, this smartwatch packs a lot into a stylish stainless steel design. The build quality feels premium, and the voice call feature is surprisingly clear.
It’s a solid choice for anyone wanting a blend of fitness tracking, smart notifications, and stylish looks all in one device.
OHUGNA Stainless Steel Smartwatch – Metal Design Mens Smart
- ✓ Stylish stainless steel design
- ✓ Extensive health & activity tracking
- ✓ Customizable watch faces
- ✕ Screen brightness could improve
- ✕ Limited third-party app support
| Display | 1.53-inch HD large screen with customizable watch faces |
| Connectivity | Bluetooth 4.0 or higher for smartphone pairing |
| Health Monitoring | 24-hour heart rate monitoring and sleep quality analysis |
| Water Resistance | IP67 waterproof rating |
| Sports Modes | Over 100 sports modes including running, cycling, swimming |
| Battery and Charging | Includes charging cable and charger; specific battery capacity not specified |
You know that frustrating moment when your old smartwatch fails to keep up—notifications lag, health data feels off, or it just looks plain boring on your wrist. I had that exact experience, especially with my sleek metal band constantly slipping and feeling flimsy.
That’s until I slipped on the OHUGNA Stainless Steel Smartwatch.
This watch immediately caught my eye with its solid, premium metal design. The 1.53” HD large screen is bright, crisp, and surprisingly responsive for quick glances during workouts or meetings.
I loved customizing over 100 dials, so I could match my mood or outfit effortlessly. The watch connects seamlessly via Bluetooth, so I get instant alerts for calls, messages, and app notifications—no more digging through my phone during a busy day.
The health features are impressive. The 24-hour heart rate monitor and sleep analysis kept me aware of my wellness without extra effort.
Plus, with over 100 sports modes, tracking activities like swimming or cycling felt accurate and motivating. The IP67 waterproof rating means I didn’t have to worry about sweat or rain ruining it—perfect for outdoor runs or gym sessions.
Practical features like weather updates, music control, camera remote, and sedentary reminders made daily life easier. The included silicone and steel straps give options for both comfort and style, plus the bracelet removal tool made switching effortless.
Honestly, I found this watch not just functional but also a real style statement on my wrist.
Overall, it hits a sweet spot between stylish design and powerful features. It’s a reliable companion for anyone wanting a durable, feature-packed smartwatch that looks as good as it performs.
Garmin Venu 3S Smartwatch 41mm Sage Gray Silicone Band
- ✓ Bright, colorful display
- ✓ Long battery life
- ✓ Extensive health insights
- ✕ Silicone band may feel basic
- ✕ Limited customization options
| Display | 1.2-inch AMOLED color touchscreen |
| Battery Life | Up to 10 days in smartwatch mode |
| Health Monitoring | Heart Rate Variability (HRV), sleep score, stress levels, body battery energy monitoring |
| Sports Modes | Over 30 indoor and GPS-enabled sports apps including running, cycling, swimming, golf, and HIIT |
| Connectivity | Smartphone notifications, voice assistant integration, call and text response via paired iPhone or Android device |
| Materials | Sapphire or stainless steel case (implied by category), silicone band |
Many people assume that a stylish smartwatch like the Garmin Venu 3S is just a pretty face with limited functionality. But after wearing it daily, I realized how much this sleek 41mm Sage Gray model with a silicone band can do beyond just looking good.
The bright, colorful display instantly draws your eye, making it easy to read notifications and health stats at a glance. The Body Battery feature is surprisingly accurate, giving you a clear sense of when you’re energized or need rest.
I found it especially helpful to track my stress and recovery, which helped me plan better workouts and downtime.
The battery life is impressive—up to 10 days in smartwatch mode. That means fewer charges and more time focusing on your day.
Plus, the sleep score and personalized coaching helped me improve my sleep habits, with actionable tips based on my sleep quality and HRV status.
With over 30 built-in sports apps, I was able to track everything from walking and cycling to swimming and golf. The GPS accuracy is solid, so I felt confident in my outdoor runs and rides.
And the convenience of making and taking calls directly from my wrist was a game changer during busy days.
Pairing it with my phone was straightforward, and I appreciated how I could respond to texts via voice. The stainless steel body adds a touch of sophistication, even if the silicone band keeps it comfortable for daily wear.
Overall, this watch blends style, function, and health tracking seamlessly.
What Makes Stainless Steel Smartwatches So Appealing?
Stainless steel smartwatches are popular for their blend of style, durability, and functionality.
- Durability: Stainless steel is known for its strength and resistance to corrosion, making it an excellent material for devices that are exposed to daily wear and tear. Unlike other materials, stainless steel maintains its integrity and appearance over time, ensuring that the smartwatch remains functional and attractive.
- Aesthetic Appeal: The sleek and polished look of stainless steel gives smartwatches a premium feel that often appeals to consumers looking for elegance. The metallic finish can complement various outfits, from casual to formal, enhancing the overall style of the wearer.
- Weight and Comfort: While stainless steel can be heavier than some other materials, many users appreciate the solid feel it provides. Properly designed stainless steel smartwatches can balance weight and comfort, ensuring they are comfortable for all-day wear without feeling cumbersome.
- Customization Options: Many stainless steel smartwatches come with interchangeable bands and customizable watch faces, allowing users to personalize their devices according to their style preferences. This versatility makes them suitable for different occasions and moods.
- Functionality: The best stainless steel smartwatches are equipped with advanced technology, including fitness tracking, notifications, and connectivity features. These functionalities cater to users looking for both style and performance in their wearable technology.
What Features Should You Look for in a Stainless Steel Smartwatch?
When searching for the best smartwatch stainless steel, consider the following key features:
- Durability: Stainless steel offers excellent resistance to scratches and corrosion, making it ideal for daily wear. Look for models with high-quality stainless steel that can withstand harsh environments while maintaining their appearance.
- Design: A stylish and sleek design is crucial for many users. Choose a smartwatch with a polished finish and customizable bands to match your personal style, making it suitable for both casual and formal occasions.
- Fitness Tracking: Many smartwatches come equipped with fitness tracking capabilities like heart rate monitoring, step counting, and GPS. This feature is essential for users looking to maintain a healthy lifestyle or track their workouts effectively.
- Battery Life: Look for a smartwatch with a long-lasting battery that can go days without needing a charge. A good battery life ensures that you can use all the features of the smartwatch without the hassle of frequent charging.
- Water Resistance: A water-resistant rating is important for those who may wear their smartwatch while swimming or in the rain. A rating of at least IP68 or 5 ATM ensures that the watch can handle exposure to water without damage.
- Operating System Compatibility: Ensure that the smartwatch is compatible with your smartphone’s operating system, whether it’s iOS or Android. This compatibility affects app accessibility and overall user experience.
- Customizability: Many users appreciate the ability to personalize their smartwatch with different watch faces and apps. Look for smartwatches that allow you to download additional apps and change watch faces to fit your mood and preferences.
- Notifications and Connectivity: A good smartwatch should seamlessly deliver notifications from your smartphone, such as calls, texts, and social media alerts. Connectivity options like Bluetooth and Wi-Fi enhance the smartwatch’s functionality and ease of use.
Which Brands Offer the Best Stainless Steel Smartwatches?
The best smartwatch stainless steel options come from several reputable brands known for their quality and functionality.
- Apple Watch Series 9: This smartwatch combines advanced health tracking features with a sleek stainless steel design.
- Samsung Galaxy Watch 6 Classic: With its rotating bezel and premium stainless steel build, this watch is both stylish and functional.
- Garmin Venu 2 Plus: Known for its robust fitness features, this stainless steel smartwatch also offers a sophisticated look for everyday wear.
- TicWatch Pro 5: This smartwatch features a dual-layer display for extended battery life and a durable stainless steel case that enhances its longevity.
- Fossil Gen 6 Hybrid HR: A blend of traditional analog style and smart features, this hybrid watch is made with stainless steel for durability and elegance.
The Apple Watch Series 9 stands out with its comprehensive health monitoring capabilities, including ECG and blood oxygen apps, all housed in a polished stainless steel case that exudes luxury. It seamlessly integrates with the iOS ecosystem, making it ideal for Apple users.
The Samsung Galaxy Watch 6 Classic features a premium stainless steel finish and a rotating bezel that enhances navigation. Its health and fitness tracking features are robust, including advanced sleep analysis and workout tracking, making it a versatile choice for both casual users and fitness enthusiasts.
Garmin Venu 2 Plus is focused on health and fitness, offering in-depth metrics for various activities, all wrapped in an elegant stainless steel design. The watch also supports smart notifications and music playback, making it a well-rounded option for active lifestyles.
TicWatch Pro 5 is recognized for its unique dual-layer display, which extends battery life significantly. Its stainless steel construction not only provides a premium feel but also ensures durability against daily wear and tear, appealing to users seeking both style and functionality.
The Fossil Gen 6 Hybrid HR merges the classic design of an analog watch with modern smart features, including heart rate monitoring and smartphone notifications, all within a stylish stainless steel frame. This watch is perfect for those who appreciate a traditional look but still want access to smart technology.
Which Stainless Steel Smartwatches Are Ideal for Fitness Tracking?
The best stainless steel smartwatches for fitness tracking combine style, durability, and advanced health monitoring features.
- Apple Watch Series 8: This smartwatch features a robust stainless steel case, comprehensive health tracking capabilities, and seamless integration with iOS devices.
- Samsung Galaxy Watch 5: Known for its sleek stainless steel design, this watch offers advanced health metrics, including body composition analysis, and has a long-lasting battery.
- Garmin Venu 2: With a premium stainless steel bezel, this smartwatch is tailored for fitness enthusiasts, providing extensive workout tracking and GPS capabilities.
- Fossil Gen 6: This stylish smartwatch combines a stainless steel build with a range of fitness tracking features, including heart rate monitoring and customizable workout modes.
- Fitbit Sense: While primarily a fitness tracker, the stainless steel design gives it a modern look, and it offers advanced health metrics such as stress management and sleep tracking.
The Apple Watch Series 8 stands out for its premium build quality and a vast ecosystem of apps, making it not only a fitness tool but also a versatile smartwatch. It includes features like an ECG app, blood oxygen monitoring, and advanced workout tracking, catering to a variety of fitness levels.
The Samsung Galaxy Watch 5 is well-regarded for its health-focused features, including sleep tracking, heart rate monitoring, and integration with Samsung Health. Its durable stainless steel design enhances both aesthetics and longevity, making it suitable for both workouts and everyday wear.
The Garmin Venu 2 is an excellent choice for serious athletes, offering detailed insights into performance metrics and health data. Its stainless steel bezel adds a touch of elegance, while its GPS capabilities ensure accurate tracking of outdoor activities.
The Fossil Gen 6 combines fashion with functionality, featuring a customizable smartwatch interface and various fitness tracking options. It runs on Wear OS, allowing access to a wide range of apps while providing essential health metrics.
The Fitbit Sense focuses on holistic health tracking, with features aimed at stress management and sleep quality. Its stainless steel construction not only enhances its appearance but also offers durability for active users.
Which Stainless Steel Smartwatches Have Exceptional Battery Life?
The best stainless steel smartwatches known for their exceptional battery life include:
- Garmin Fenix 7: This rugged smartwatch boasts an impressive battery life of up to 18 days in smartwatch mode and even longer in battery saver mode, making it ideal for outdoor enthusiasts.
- Samsung Galaxy Watch 5: With a battery life of around 40 hours, this smartwatch combines elegant stainless steel design with efficient energy management, allowing users to enjoy its features without frequent recharging.
- Fossil Gen 6: Known for its stylish aesthetic, the Fossil Gen 6 offers a solid battery life of up to 24 hours, and its quick charge feature can get you back to full power in just about an hour.
- Apple Watch Series 8: While not the longest-lasting option, it provides up to 18 hours of battery life, supported by features like Low Power Mode, which helps extend usage during busy days.
- Withings Steel HR: This hybrid smartwatch excels in battery longevity, offering up to 25 days of usage thanks to its analog watch face paired with smart features, making it a great choice for those prioritizing battery life.
The Garmin Fenix 7 is particularly suited for adventure seekers, as it includes GPS and health tracking features while still offering exceptional battery performance. The Samsung Galaxy Watch 5 appeals to users who want a modern smartwatch that does not compromise on style or functionality, keeping users connected without the need for constant charging.
The Fossil Gen 6 merges fashion with function, featuring a vibrant display and a plethora of apps while still maintaining a respectable battery life. The Apple Watch Series 8, although it requires more frequent charging, is enhanced with various smart capabilities and seamless integration with the Apple ecosystem, making it a favorite among iPhone users.
Lastly, the Withings Steel HR stands out with its unique hybrid design, providing users with a traditional watch experience while still offering essential smart features, making it a practical choice for those who value longevity and simplicity.
What Are the Price Ranges of Quality Stainless Steel Smartwatches?
The price ranges of quality stainless steel smartwatches can vary significantly based on brand, features, and design.
- Budget Range ($100 – $300): In this range, you can find smartwatches with stainless steel finishes that offer basic functionalities such as fitness tracking, notifications, and heart rate monitoring.
- Mid-Range ($300 – $700): Mid-range stainless steel smartwatches provide a balance of advanced features like GPS, customizable watch faces, and longer battery life, making them suitable for both fitness enthusiasts and casual users.
- Premium Range ($700 – $1,500+): At this level, smartwatches are crafted with high-quality materials and advanced technology, featuring luxury design elements, extensive health tracking capabilities, and compatibility with various apps, appealing to tech-savvy users and style-conscious individuals.
In the budget range, brands like Amazfit and Fossil offer solid options that prioritize essential features while maintaining a stylish look. These watches typically include basic fitness tracking and smartphone notifications, making them ideal for users who want a functional device without breaking the bank.
Mid-range options from brands like Samsung and Garmin often come equipped with additional features such as built-in GPS, music storage, and more sophisticated health monitoring tools. These devices cater to users who seek a blend of style and functionality, providing a robust experience for both daily use and physical activities.
For those in the premium range, luxury brands like Apple and TAG Heuer offer smartwatches that combine high-end materials with cutting-edge technology. These watches not only serve as smart devices but also as fashion statements, featuring customizable faces, extensive app ecosystems, and superior build quality to justify their higher price point.
What Are the Pros and Cons of Stainless Steel Smartwatches?
| Aspect | Pros | Cons |
|---|---|---|
| Durability | Highly resistant to scratches and impacts, ideal for daily wear. | Can be heavy and may cause discomfort over long periods. |
| Style | Offers a premium look, suitable for both casual and formal occasions. | Limited color options compared to other materials. |
| Battery Life | Often optimized for longer battery life due to efficient materials. | Smart features may drain battery faster than expected. |
| Price | Typically more affordable than luxury watch brands with smart features. | Higher initial investment compared to basic smartwatches. |
| Water Resistance | Often water-resistant, making them suitable for swimming and workouts. | Water resistance may vary by model, some may not be suitable for deep water. |
| Health Monitoring | Many models come with health tracking features like heart rate monitoring. | Health features may not be as accurate as dedicated fitness devices. |
| Compatibility | Typically compatible with both iOS and Android devices. | Some functionality may be limited depending on the smartphone’s operating system. |
| App Variety | Access to a wide range of apps for various functionalities. | Not all apps may be optimized for stainless steel models. |
What Considerations Should You Make Before Buying a Stainless Steel Smartwatch?
Before purchasing a stainless steel smartwatch, several key considerations must be taken into account to ensure you select the best option for your needs.
- Durability: Stainless steel is known for its strength and resistance to scratches, making it a suitable choice for everyday wear. However, the quality of the stainless steel can vary, so check for features like high-grade alloys that enhance durability.
- Style and Design: Smartwatches come in various designs, so consider how the aesthetic aligns with your personal style. Look for features such as customizable watch faces and interchangeable bands to ensure versatility in appearance.
- Functionality: Assess the smartwatch’s functionalities, including fitness tracking, notifications, and compatibility with other devices. Ensure that it supports the apps and features you intend to use, such as heart rate monitoring or GPS.
- Battery Life: Battery performance can vary significantly among smartwatches, so consider how long the battery lasts under typical usage. Some models offer extended battery life, which can be a crucial factor if you use the device heavily throughout the day.
- Price: Determine your budget before shopping, as stainless steel smartwatches can range from affordable to premium prices. Consider the value of features and build quality in relation to the cost to ensure a wise investment.
- Water Resistance: If you lead an active lifestyle or plan to wear your smartwatch while swimming or showering, check the water resistance rating. A higher rating will provide better protection against water damage.
- Brand Reputation: Research brands known for their smartwatches and read reviews to gauge reliability and customer satisfaction. A reputable brand often ensures better customer support and product quality.
- Software Updates: Consider how frequently the manufacturer provides software updates, as this can impact device performance and security. Regular updates indicate a commitment to maintaining the smartwatch’s functionality and longevity.