GPS speedometer: G20 Special reminder:The working voltage of this product is 5V. Modification of installation lines and the voltage higher than 5V is prohibited. First time installation: Plug the MICOR-end of thepower cordinto the product and the other end into the car USB port. After the product is powered on, it needs to wait to search for satellite signals. When "-" turnsto "0", it means that the satellite has been connected and can be use dnormally.<br><br>Display functions: 1. Ambient Light(Shortpress the wheel to close) 2. Compass: N:north, S:south, W: west, E:east 3. Vehicle speed andunit: MPH:mile, Km/H:kilometer Colour:As Shown Material:ABS+PC<br><br>Package Contents: 1 * car mounted HUD head up display 1 * USB cable<br><br>Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.