Sierra 781-579-080P Amega Series Speedometer GPS GaugeFeatures: Dial Range: 0-80 MPH; Sender Code: GPS Receiver; 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; Black dial, red graduations, white numerals, vivid white pointer staff; Scratch resistant curved glass lenses, with black, near-flush bezels; U.S. and metric scales; Perimeter and thru-dial lighting; Optional add-on eyebrow or square bezels available (see Gauge Accessories for details;