Specifications:
Brand: Xiaomi
Model: Mi Band 4
Color: Black
Waterproof Level: 5ATM
Screen Type: AMOLED
Screen Size: 0.95"
Screen Resolution: 120 X 240 RGB
Screen Color: 24bit
Screen Backlight: Maximum Brightness ≥400nit, Adjustable
Touch Screen: On Cell Dual Point Mutual Capacitive Type
Cover Plate Material: 2.5D Reinforced Glass + AF Coating
Button: 1 Touch Button (Wake Up, Return)
Payment: Support for Alipay QR Code Payment
Wristband: Removable Wristband
Band Width: 18mm/0.71"
Wristband Material: TPU
Adjustable Length: 155-216mm/6.1-8.5"
Memory: 512 KB
Flash Memory: 16MB
Connection: BT5.0 BLE
Charging Mode: 2Pin Pogo Pin
Charging Time: ≤2 Hours
Vibration Motor: Rotor Motor
Case Material: PC Plastic
APP: for Xiaomi Sports APP
System Support: for Android 4.4, iOS 9.0 or Later 
Sensors:
Triaxial Acceleration Sensor + Triaxial Gyroscope
Self-Developed PPG Heart Rate Sensor
Capacitive Wear Monitoring Sensor
Battery: LiPo, 135mAh
Battery Endurance: ≥20 Days
Weight: 22g
Product Size: 46.9 X 17.9 X 12mm/1.85 X 0.7 X 0.47"

Notes:
1. Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you!
2. Please allow 1-3mm measuring deviation due to manual measurement.
Included:

1 X Smart Wristband
1 X Wrist Strap
1 X Special Charging Cable
1 X User Manual