Audio2000's 6952umh UHF 200 Frequency Portable Wireless Lavalier/headset Microphone UHF Band 551 - 581 Mhz with Selectable frequency that can be changed manually or automatically 100 Adjustable Channels per transmitter. These 100 have 6 sub-channels each (Totals 1200 selectable frequencies to be help with fine tuning) One 3.5mm TRS earphone output and level control on the front panel One 3.5mm TRS AUX output on rear panel w/ Two Independent Volume Control Knobs (One for Each Channel) Operating Range up to 300ft (within line of sight)