The Sennheiser SKM 100 G4-S is a handheld wireless microphone transmitter compatible with the EM 100 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 provides up to 8 hours of operation on two AA batteries, with a fixed 30mW RF power output and a transmission range up to 330'.