Open a 3-3/8 inch dimension and 2-3/4 inch depth hole, put gauge into it and fasten. Hook up easily, 3 wires connection(power, ground, lighting). This is complete unit, can work directly with sensor together, not need other sensor cables. Mount the sensor at any position, on or under the dashboard. It takes about to get signal in the first time, but less than 3 seconds after that. It gets quicker under a clear view of the . Sometimes if signal is missing, pls. reconnect all wires and restart it. It shows current speed and odometer(cannot be reset), no trip meter. Speedometer Less power consumption, longer life, higher precision,quick location confirmation, short start up time. Speedometer: 220Km/h Voltage: 12V/24V Applicable models: Universal Colour: As shown Material: ABS+metal Size: 75mmx90mmx85mm Package Contents: 1 * 220Km/h Speedmeter 1 * Chinese and English manual 1 * Multi-plug socket 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.