The ew IEM G4 Wireless Monitor System from Sennheiser is part of the evolution family of wireless monitoring systems and includes an SR IEM G4 transmitter, a EK IEM G4 stereo receiver, a pair of IE 4 earphones, a rod antenna, GA 3 rackmount kit, and two AA batteries. This kit can be used as a rugged, all-in-one wireless in-ear monitoring system for live stage, theater, and house of worship applications. The system provides up to 1680 frequencies tunable in 25 kHz steps to deliver clear, audio without interference and dropouts. Additional transmitters and receivers can be added for up to 16 wireless IEM channels.