How to Use: 1. Press and hold on/off key (non board side key) to turn on/off machine 2. Short press on/key to switch modes (low frequency mode, high frequency mode) 3. Short press power level key (side key) to cycle through the power (up to 3 powers) 4. The default low frequency mode is turned on, the strength is 1 5. Stop working when power is low, and turn off after the 4th light flashes 5 times 6. It does not work when charging. When battery is not fully charged, the fourth light will flash quickly. When fully charged, the fourth light is always on 7. Please turn off power after 20 minutes of inactivity Specification: Item Type: Sleep Aid Device Built In Battery: Lithium Battery 150mAh Mode: Two Modes Gear Position: 3 Gears Package List: 1 x Sleep Aid Device 1 x USB Cable 1 x Manual 1 x Lanyard