Shure FP1 Wireless Bodypack Transmitter, J3 For this wireless system component to work, please make sure your transmitter and receiver match in frequency range (style) Automatic transmitter setup that instantly syncs the transmitter to the receiver frequency LED indicator for control lockout, IR RF sync, and low battery Audio input gain for adjustment of audio level 4-Pin microphone input jack for use with lavaliers or headset microphones with TA4F connectors