Sierra 781-684-080P Eclipse Series GPS SpeedometerFeatures: Dial Range: 0-80 MPH; Size: 3"; Included LCD heading display to show course over ground; Use our GPS antenna (sold sep) or connect to an existing NMEA 0183 GPS device - connectors included; Speed accuracy of +/-1 MPH (once moving); Heading accuracy of +/-1 degree (once moving); Ideal for slow speed apps like pontoon boats and for high speed performance boats w/ pitot tubes; Scratch-resistant domed glass lens; Perimeter lighting for excellent readability at night; U.S. and metric scales; Optional add-on eyebrow or square bezels available (see Gauge Accessories for details;