Usage Tips: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, quick location confirmation and short start up time. IP67 waterproof and dustproof grade Stepper motors used for full range of stepping gauges, great feature with its less power consumption, longer life, higher precision, etc. installation : 1.Turn it on, then the to search the signal and LCD will display "gps---" ,if there is still no GPS signal after three minute, LCD displays "Err". 2.Short press the button to change the backlight color: Backlight changed in sequence: red (default) green blue white yellow cyan Purple (automatic).Automatic: Automatically switch the backlight color every 20 seconds, Cycle switch according to the above sequence. Wiring 1Black: Ground(-) 2Red: 9-30VDC 3Yellow: Backlight Indicating Rangel: 0-30KM/H Colour:Silver Backlight: 7Color Material:Stainless steel + plastic Size: 85mm(3-3/8 inch) 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.