The SKM 100 G4-S Handheld Transmitter with Mute Switch, No Capsule from Sennheiser is intended for use with the G4 series of wireless receivers and a microphone capsule (available separately). The transmitter features infrared-sync, for quick and easy channel syncing between the transmitter and receiver. It is built with a lightweight and rugged aluminum housing and delivers pristine audio reproduction of both speech and performance vocals. Two AA batteries power the transmitter, and it is equipped with contacts for recharging the optional BA 2015 accupack battery, without having to remove it from the transmitter itself.