Mi Band 4.

Sport Functions: 6 workout modes: Treadmill, exercise, outdoor running, cycling, walking, pool swimming; Count steps, distance, and calories burned.

Health monitoring: Workout completion notifications, goal setting, sleep monitoring, heart rate monitoring, all-day heart rate checking, resting heart rate, heart rate chart, idle alerts.

Other features: Alarm, proximity sensor, pre-set watch face, customizable watch face, lock screen, timer, stopwatch, phone alarm and notifications, incoming calls, message notifications, calendar notifications, app notifications, weather forecast, Find my phone, phone unlock, event notification, Night mode, Do not disturb mode (works even without phone), music controls on band, Bluetooth broadcasting, battery level display, different ways to wear, OTA updates.

Features.

Display.

• 0.95" inch AMOLED display
• Resolution: 120 x 240 RGB
• Screen Brightness: Up to 400 nits (max brightness), brightness adjustable

Body.

• Weight: 22.1g
• Wrist strap type: Removable wrist strap Removable wrist strap (Mi Smart Band 4 is compatible with Mi Band 3 straps)
• Wristband width: 18mm
• Wrist strap material: Thermoplastic polyurethane
  

Memory.

• RAM: 512 kb
• ROM: 16 mb

Connectivity.

• Wireless connectivity: BT5.0 BLE

Other Features.

• Sensors: 3-axis accelerometer + 3-axis gyroscope; PPG heart rate sensor; Capacitive proximity sensor
• System requirements: Android 4.4, iOS 9.0 or above

Battery.

• Battery: LiPo, 135mAh
• Charging Type: 2Pin Pogo Pin
• Charging time: ≤ 2 hours
• Standby time: Up to 20 days