Specifications:

Battery : 70mAh , standby time 300 hours 
Input Voltage : 5V
Weight : 6.9g
Material : ABS
Strap length : 23.5cm ; Adjustable length : 155-21cm
Screen : 0.42" OLED 
Bluetooth : 4.0
Waterproof : IP67 (not suitable for swimming or bathing)
Functions : Heart rate monitor, Sleeping monitor, Messaging notification, Caller ID display, Pedometer, Smart alarm, etc