Chesepeake Black 4 Studded Speedometer - 60MPH GPSThe 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