Chesapeake Black SS 4 Speedometer 60MPH GPS . 4 Hole Size 3.375 85mm . The GPS Speedometer is a drop in replacement for your current speedometer to match your existing instrument dash. GPS information is gathered from an internal GPS antenna. No external antenna required. The Faria GPS Speedometer uses a highly accurate 48 channel GPS receiver. You can be sure that the Faria GPS Speedometer is giving you the most accurate GPS information available on the market today. Course Over Ground COG and actual heading compass heading over ground are displayed on the optional digital LCD. 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. Benefits No external GPS antenna required. Premium LED back-lit dials. Ultra fast Satellite acquisition time TTFF 1 second from Hot start. Speed Accuracy of /- 1 MPH. Heading Accuracy of /- 1 Degree. Digital stepper motor 4 Hole Size 3.375 85mm . The GPS Speedometer is a drop in replacement for your current speedome GPS information is gathered from an internal GPS antenna. No external antenna required. The Faria GP Speed data is shown by an analog pointer. This pointer is driven by a digital stepper motor for incr No external GPS antenna required. Premium LED back-lit dials Ultra fast Satellite acquisition time TTFF 1 second from Hot start Speed Accuracy of /- 1 MPH Hea