This GPS speedometer provides accurate speed over ground readings and heading information all in one attractive package. Can be connected to an existing NMEA 0183 receiver or be used with a custom designed GPS receiver/antenna (item #93565). Ideal for all speed applications and particularly useful for craft where traditional speed sensors like pitot tubes and paddlewheels do not perform well. An additional benefit is there are no elements that can corrode or break. Sierra Part #781-627-035P.• Included LCD heading display to show course over ground• Use GPS antenna (sold separately) 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 with pitot tubes• Full automotive type lighting with no "halo" around dial edges• When illuminated, black dial grads become red, pointer lights red• Black dial, white graduations/numerals (metrics in blue), white pointer staff• Scratch-resistant curved glass lenses with polished stainless steel near-flush bezels• Fog-Resistant Design! Complies with SAE J-1810• Sender Code: GPS Receiver Useful for all types of watercraft | Sierra Premier Pro 3" GPS Speedometer With LCD, 35 MPH in White