The WL/T-PRO-S VHF Wireless Bodypack Transmitter comes complete with the EX-503 "Electret " condenser omni-directional lavalier microphone. This is the "S" frequency 2-channel switchable (171.105MHz and 171.845MHz) body-pack transmitter for all "PROs" series receivers. It uses a single 9V alkaline battery and comes with a belt-clip. Technical Specs: Modulation system: FM Sensitivity: 94dB SPL @ +/- 2.5KHz deviation Battery: 1-9V Power consumption: 30mA Dimensions: 86(h) x 60(w) x 21.5(d)mm (3.3" x 2.4" x 0.85") Weight 1.00 lbs