Sennheiser ew IEM G4 Twin A-Band, Evolution Wireless In Ear System, Consists of 2 x UHF bodypack receiver (EK IEM G4), 9.5"" transmitter (SR IEM G4) and 2 x 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 channels, Frequency response 25 to 15,000 Hz, Frequency transmission via infrared interface, Pocket receiver with charging contacts for optional rechargeable battery BA 2015 (NiMH), Pilot tone, Autotune to find free frequencies, Audio Gain includes 60 dB, 4-Digit battery indicator on the transmitter and receiver, HDX compander, OLED display with NF level and channel display, 3.5 mm jack for earphones, Adjustable limiter, Switchable transmission power 10/30/50 mW, WSM support (Ethernet interface for Frequency Management), Adjustable 6.3mm headphone jack on the transmitter, 1 x BNC antenna socket, Inputs 2 x Jack / XLR female balanced combo, Power supply 10.5 - 16 V DC, Includes power supply NT 2-3 CW, 2 Earphones IE 4, 4 x 1.5V battery, Rack kit GA 3 for 19"" installation included, Frequency range A-band: 516 - 558 MHz