Suitable for all vehicles, boats, and off-road vehicles. The signal comes directly from the satellite signal receiver (GPS speed sensor). The gauge has the advantages of high precision, fast location confirmation, and short startup time. IP67 waterproof and dustproof stepper motors used for the full range of stepping gauges, great features with lower power consumption, longer lifespan, higher precision, etc. Installation: 1. Power it on, then it will search for the signal and the LCD will display \"gps---\". If there is still no GPS signal after three minutes, the LCD will display \"Err\". 2. Short press the button to change the backlight color: The backlight changes in order: red (default) green blue white yellow cyan purple (automatic). Automatic: Automatically change the backlight color every 20 seconds, cyclically switching according to the sequence above. Wiring 1 Black: Ground (-) 2 Red: 9-30VDC 3 Yellow: Backlight Indication range: 0-60 Color: Silver Backlight: 7 colors Material: Stainless steel + plastic Size: 85mm Package contents: 1 x GPS speedometer; 1 x GPS antenna Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture to be a little different from the real thing. The allowed measurement error is +/- 1-3 cm.