Audio 2000s AWM6528U630 4 Channel UHF Wireless Microphone with Mini Headsets UHF Band Frequency 551MHz - 581MHz (comply with new FCC rules) 50 Selectacble frequencies per channel and up to 12 systems can be used simultaneously. Four Independent XLR Balanced Audio Outputs One 1/4" (TS) Unbalanced Mixed Audio Output Four Volume Control Knobs (One for Each Channel) at the Front Panel