The Sennheiser AB 3700 Broadband Antenna Booster is an inline RF signal booster for the Sennheiser EM3731, EM3732 and EM3732 Command receivers. The antenna significantly boosts RF strength and gain during long BNC cable runs. The AB 3700 features up to 15dB of amplification and mounts to a standard 3/8" or 5/8" stud.