Nady HT-1KU Handheld Microphone Transmitter for W-1KU, 2W-1KU, and 4W-1KU wireless systems. This system is Band 3 : 520.0-544.9MHz - This frequency band is fully compliant with the most up-to-date FCC regulations and operates on 520.0-544.9MHz frequency bands which are comprehensively available for unlicensed wireless microphone use throughout the Continental United States.