Yihao Gps Antenna For Bnc Garmin Gpsmap 215 220 225 230 232 235 Sounder 238 276C 298C Amplified (active) GPS antenna to enhance and improve GPS signal reception. Built-in magnets for mounting on car rooftops or other metallic surfaces. Gain=28dB,RHCP,Z=50R, Center Frequency 1575.42MHz3MHz Threaded holes for mounting on aircraft fuselage, boat surfaces or car/RV/SUV vehicle surfaces. Length: 3 m (9.7 feet)