Amazfit has launched three new long-lasting smart activity watches: the GTR 3 Pro, priced at $229.99, and the GTR 3 and GTS 3, both priced at $179.99. The GTR 3 can go up to 21 days of typical usage before needing a recharge, the company claims, while the GTR 3 Pro and GTS 3 can last for about 12 days. These watches all run Zepp OS, which plays nicely with both iOS / Apple Health and Android / Google Fit. They can also sync your health and activity data to Strava, Runkeeper, and others. The GTR 3 Pro is the company’s new flagship fashion fitness watch. It includes Wi-Fi, GPS, 2.3GB of on-board music storage and Bluetooth audio and call support underneath that round 1.45-inch 331ppi OLED touchscreen display. It’s water resistant to a depth of 50 meters, and a new BioTracker 3.0 optical sensor can measure heart rate, blood-oxygen, stress, and respiratory rate in less than 45 seconds. Amazfit says its watches can track over 150 sports, with eight activities recognised automatically to help you avoid forgetting to track common activities like running, swimming etc.