1, To ensure proper use, make sure the battery is fully charged
2, Connect the earphones
3, Turn the main switch clockwise to turn the device on
4, you can adjust the volume until you hear a clear voice or a clear sound
5, The device provides the highest audio gain by several 2000 times
6, you can hear through cement walls, steel walls, wooden walls, glass cavity bricks, etc.
• Dimensions: 43 mm x 36 mm
• Power supply: Built-in rechargeable battery