Audio-Technica ATW-1811C 1800 Series Camera Mount UHF Wireless Microphone System Operating frequency of 541.500 - 566.375 MHz (TV Channels 25 - 30) Two completely independent receiver channels in a single unit, for simultaneous operation of two microphones (dual-channel systems) Compact receiver is easy to mount on a camera Automatic frequency scanning for easy selection of open channels Tone Lock squelch system eliminates interference when transmitter is off Includes ATW-R1810 single-channel receiver, ATW-T1801 UniPak body-pack transmitter and a lavalier microphone