A Complete System Which Includes The Wl/t-pro A Belt-pack Transmitter (wm-pro) With Electret Condenser Lavalier Microphone (ex-503) And The Wr-pro Receiver Which Comes With Both Shoe-mount And Hook And Loop Fastener. All Receivers And Transmitters In The “pro” Series Are On The Same 2 Frequencies (169.445mhz And 170.245mhz).LEDs on transmitter and receiver to confirm system status. Earphone included to monitor sound that is being recorded. Receiver plugs into camera’s external microphone jack. Both units use one 9V battery each. Includes WR-PRO receiver, WM-PRO belt-pack transmitter, and lavaliere electret condenser microphone.