SPECIFICATION: Charging interface: Standard V8 USB interface Battery Capacity: 500mAH/3.7V Power Supply: 5V Power consumption: 0.4W Charging Time: Approximate 1 hours Charging Voltage: 5V Net Weight: 85g Material: ABS+ High elastic nylon belt Range of Application: 15kg-95kg PACKAGING LIST: User manual1 Posture corrector1 USB charging cable*1 OPERATION: 1. First adjust the harness to the suitable length. 2. Hold the switch for 1 second to power on the reminder, the blue light will light up and it will shake 3 times, which means it is working normally. 3. Keep the right posture until the appliance vibrates 3 times. At the same time, the reminder has recorded your correct posture. 4. When you have a hunchback, the reminder will automatically identify it and then release vibration to remind you to keep your chest straight. NOTE: 1. If you can’t turn on the machine , please charge it for 10 minutes first. If there is still no response, you can contact with us, we will give you a satisfied solution. 2. The correction process is not easy, and it takes effect only after persistence. 3. If the posture corrector is not sensitive, you can tighten the harness properly. At the same time, the back should be straight and the chest should be spread as far as possible during initialization.