Sennheiser XSW 72-A XS Instrument System - SK 20,  CL1 Cable and EM 10 Receiver - "A" 548-572 MHz True Diversity reception for worry-free operation 8 frequency banks containing 12 coordinated channels each, 960 available frequencies tunable in 25 kHz steps Up to 250 feet of transmission range Illuminated audio mute button on transmitters Balanced (XLR) and unbalanced (1/4") outputs