Garmin StreetPilot III, GPS V III+ Sounder GPSMap 178C 188 276C 298c 398c 498c iCOM 270ML 370ML External GPS Antenna (BNC) Amplified (active) GPS antenna to enhance and improve GPS signal reception. Garmin compatible GPS Antenna for StreetPilot, GPS II III V Built-in magnets for mounting on car rooftops or other metallic surfaces Right Angle BNC connector, which permits maneuverability on dashboards, in backpacks, carrying cases and tight places. Built-in permanent mounting holes for mounting on aircraft fuselage, boat surfaces or car/RV/SUV vehicle surfaces.