The Sennheiser EK IEM G4 Wireless Receiver features a robust design and delivers exceptional clarity across the entire frequency spectrum. With complete compatibility with Sennheisers WSM control software the EK IEM G4 features flexible frequency allocation and is compatible with up to 16 channels. The receiver can be powered via two AA batteries or with Sennheisers BA 2015 rechargeable battery (not included). The EK IEM G4 comes complete with a pair of IE 4 earphones providing you with a high-performance IEM receiver with a transmission range of up to 100 meters (300 feet).