Xiaomi Mi band 4

Display: 0.95 inch AMOLED, full color touch screen;
Colour depth: 24bit;
Screen brightness: Up to 400 nits;
Resolution: 120 x 240;
Button: Single touch button (wake up, go back);
Connectivity: Bluetooth version 5.0 BLE; NFC on some models;
Mass: 22.1 g;
RAM: 512KB;
Storage: 16MB:
Battery: LiPo, 135mAh, 20 days of battery life;
Sensors: accelerometer, gyroscope, PPG heart rate sensor, capacitive proximity sensor;
Waterproof: up to 50 metres, 5 atmospheres