1Characteristic: Three unit can be switched, that is km/h; mph; knot(rounded to one decimals). Tft screen, displays the range clearly, and 9?32VDC working voltage. 2Application: Gps speedometer fits for car, tractor, truck, boat, marine, motorcycle etc, and can be used for the engines generating units, ships, construction machinery, agricultural machinery, automotive modification, etc. 3IP67 Waterproof: Made of 316L stainless steel, speed gauge can be used for a long time even in acid base and humid environments. IP67 waterproof and dustproof rating. with curved glass (antifog function). 4Firmly Installed: There is a snap together with the harness connector, for best and firmly connected, the gauges could work even in strong viberation. 5Easy to Operate: Open a 85mm (3/8in) and 55mm( 2 3/16in) depth hole to put the gauge into it. After connection, it takes about 30 seconds to get signal in the first time. It gets quicker under a clear view of the sky.