Operating system Zepp OS Memory storage capacity 4 GB Special features 450 mAh, 5 ATM, Amoled, BioTracker, GPS Battery capacity 450 Connectivity technology GPS, Bluetooth About this item Clear & Easy to read Ultra HD AMOLED Display: With unprecedented visual clarity that reaches 331 ppi, the large 1.45 inch screen of the Amazfit GTR 3 Pro activity tracker shows you exactly what you want, when you want it, and is visible even under bright sunlight. The ultra HD AMOLED display boasts a 70.6% screen to body ratio, which is among the for round smartwatches that are currently available. Test Four Health Metrics in One Tap: With the Amazfit GTR 3 Pro fitness watch you can test your heart rate, blood oxygen saturation, stress level and breathing rate in a single tap of the watch and get a result in as little as 45 seconds. To easily understand your condition without cycling through individual apps, quickly get the data you need in one tap and then get on with your day. A Fitness Partner with 150+ Sports Modes: Whether you're a team player or prefer the focus of working out by yourself, the Amazfit GTR 3 Pro sports watch is the ultimate easy to use sports smartwatch. With over 150 built in sports modes to suit your choice of activity, the watch can track metrics like heart rate, calories burned, and more. Listen to Your Music & Receive Bluetooth Calls: When you're out for a walk, working out, or seeing friends, you can leave your phone in your pocket. Through Bluetooth connection to your phone, the Amazfit GTR 3 Pro smart watch can receive phone calls, and also be used to easily control the music on your phone. You can even store up to 470 songs on the watch for independent music playback. High Precision GPS and 5 ATM Water Resistance: The Amazfit GTR 3 Pro sports watch has a built in barometric altimeter to help keep an eye on the altitude and air pressure of your outdoor activities, and supports GPS, GLONASS, Galileo, BDS and QZSS satellite navigation systems to accurately track your route. And it also has achieved a water resistance grade of 5 ATM, so you can enjoy the sea or take a dip in a pool without worry. clasp type : Tang Buckle