The MXL AC-40EXT is the extension microphone for the USB web conference series. Featuring sturdy metal construction, this high quality 15" gooseneck microphone is fully adjustable. Anywhere from one to four mics can be used, all powered by the central USB mic. Each mic has it"s own mute switch. The user can mute each mic individually. Central USB mics include the AC-406 and AC-400.