Oklahoma Sound LWM-6 Lectern Wireless Tie-Clip/Lapel/Lavalier Microphone, Designed only for Use with Wireless-Ready Lecterns from Oklahoma Sound (Black) Select channel A or B to eliminate outside frequency interruption Move freely up to 200 ft. away Includes pocket-size transmitter with a clip-on mic Uses a 9-volt battery Designed only for use with wireless-ready lecterns from Oklahoma Sound. These include the 800X series, 111PLS series, and the 6010 series. It does not work with the PRA-7000 or any other sound system