The Sennheiser SKM 500 G4 is a handheld wireless microphone transmitter compatible with the EM 300-500 G4 wireless receiver. It features an interchangeable microphone capsule design and is offered without a capsule included, so you can choose the one that best fits your application. The transmitter operates on a wide 50 MHz UHF tuning range with 2000 selectable frequencies available. It provides up to 8 hours of operation on two AA batteries, with a transmission range up to 330 feet and a selectable 10/30/50mW RF power output for overcoming interference in difficult RF environments.