Open a 3-3/8 inch diameter and 2-3/4 inch depth hole, insert the gauge, and secure it in place. Easy installation with 3-wire connection: power, ground, and lighting. This is a complete unit that works directly with a GPS sensor; no additional sensor cables required. Mount the sensor in any position, on or under the dashboard. Takes approximately 30 seconds to acquire signal the first time, and less than 3 seconds thereafter. Signal acquisition is faster under a clear view of the sky. If signal is lost, disconnect and reconnect all wires and restart the device. Displays current speed and odometer (non-resettable); does not include a trip meter. CNSPEED Speedometer features low power consumption, extended lifespan, high precision, quick location confirmation, and short startup time. Speedometer range: 220 km/h Voltage: 12V/24V Application: Universal Color: As shown Material: ABS + metal Dimensions: 75mm x 90mm x 85mm Package Contents: 1 x 220 km/h Speedometer 1 x User Manual (English and Chinese) 1 x Multi-plug socket Note: Light shooting and different displays may cause the color of the item in the picture to appear slightly different from the actual product. Measurement error allowance is +/- 1-3 cm.