A drop in replacement for your current speedometer to match your existing instrument dash with an internal GPS antenna. No external antenna required. The GPS Speedometer uses a highly accurate 48 channel GPS receiver. Speed data is shown by an analog pointer. This pointer is driven by a digital stepper motor for increased accuracy and minimized pointer bounce during vessel operation. Chesapeake Series features a polished stainless steel bezel, domed glass lens and a premium LED back-lit dial. Requires 3-3/8" hole. Studded harness fits into existing dash harnesses already installed. The studded speedometer connects directly to the battery and ground without a costly connector. LCD display shows Compass Rose heading and actual heading (COG)Fast satellite acquisition time (TTFF) 1 second from Hot StartSpeed accuracy of +/- 1 MPHDigital stepper motor driven pointersPerfect for slow moving vessels where pitot tubes just don't workIdeal replacement for speed sensing devices (pitot tube and paddle wheel) that can fail over time