The Garmin GA 25BNC provides an amplified GPS signal for when you need more power. It comes with nine-and-a-half feet of cable and is also available in GA 25MCX, depending on which unit you have. Unlike the GA-27C, the GA 25 has an integrated magnetic mount only and no low-voltage mode, so it will put a greater drain on your batteries.
Works with GPSMAPs 376C, 276C, 198C, 188C, 178C, 188, 178, 192C, 182C, 172C, 182, 172, GPS V, StreetPilot III and select other models.