LD Systems U508 CS 4, 4-Channel Wireless True Diversity UHF Conference System, Frequency range (UHF): 823 - 832 MHz and 863 - 865 MHz, 4 Microphone units with table base (operation with 2x AA battery) and gooseneck microphone, Automatic channel search, Automatic frequency search, Infrared frequency synchronisation of receiver and microphone unit, Pilot tone, Priority circuit, RS-232 interface for external control, Audio output balanced: 4x XLR, Audio output