Sennheiser ew IEM G4 C-Band, Evolution Wireless In Ear System, Consists of UHF bodypack receiver (EK IEM G4), 9.5"" transmitter (SR IEM G4) and IE4 earphones, Stereo / focus / mono modes, Up to 1680 frequencies in 42 MHz switching bandwidth, 20 Channel banks each with up to 16 presets, Up to 16 compatible