Audio Technica PRO301H Pro3Series Headset VHT Wireless System - Channel T3 Advanced dipole antenna design for extended operating range, which improves operation by providing a ground element in addition to the usual signal element. Volume control, AF Peak, RF and Power indicator lights, 1/4" output jack and space-saving power supply. Easily accessible On/Standby/Off switch on transmitters. Available in three VHF travelling frequencies (169.505, 170.245, and 171.905 MHz). All three work together with no interference from TV channels, and no frequency coordination is required. Professional locking connector on Uni-Pak body pack transmitter