XIAOMI MI SMART BAND 4 black

The Xiaomi Mi Smart Band 4 is a fitness tracker that features a 0.95-inch AMOLED color touchscreen, 24/7 heart rate monitoring, and 5ATM water resistance for swimming. Key manufacturer-highlighted features include its ability to track various sports, display notifications and call alerts, control music playback, and provide long battery life, with a 2-hour charge lasting up to 15-20 days.  
Key features
Display: 0.95-inch AMOLED color full-touch screen. 
Water resistance: 5ATM (waterproof up to 50 meters), with automatic swim style detection. 
Health tracking:
24/7 heart rate monitoring with high-heart rate alerts. 
Automatic sleep detection and analysis. 
Sedentary reminders. 
Sports and fitness tracking:
Tracks running, walking, cycling, and swimming. 
Step counter and goal setting. 
Can track 12 different data points during swims. 
Smart features:
Music control (play, pause, volume). 
Call and message notifications, with ability to reject calls. 
Screen lock, timer, and countdown. 
Find your phone and alarm clock functions. 
Weather forecast. 
Connectivity: Bluetooth 5.0. 
Battery:
Standard version: Up to 20 days on a single charge, takes about 2 hours to fully charge. 
NFC version: Up to 15 days on a single charge. 
NFC version (additional features): Supports transportation cards and  offline payments, and uses the Xiao Ai voice assistant (Chinese language only).