Audio-Technica PRO-501/H Pro Series 5 Frequency-Agile Diversity UHF Wireless Headworn Microphone System 8selectable frequency-coordinated UHF channels; Use up to 8 simultaneous systemsall channels compatible Automatic frequency scanning Diversity operation for increased range/reliability LED Channel display plus Antenna, AF Peak indicators Balanced XLR and unbalanced  output connectors Includes PRO-R500 receiver, PRO-T501 UniPak transmitter with PRO 8HEcW headworn microphone, and system storage case