Crystal-Clear Display & Enduring Power The Xiaomi Smart Band 9 features a vibrant 1.62″ AMOLED display, up to 21 days battery life on its 233 mAh battery, and over 150 workout modes. With Bluetooth 5.4 and 50 m water resistance, it’s a top waterproof fitness tracker smartwatch and one of the best fitness trackers you can buy. What Is…