Sennheiser Spectera SEK UHF - Bidirectional Bodypack Transceiver (470-608 MHz)Each bidirectional Spectera SEK body pack manages both an IEM IFB and a mic line stream simultaneously. Plus, they allow for full remote control and monitoring, via identical RF connection, of IEM volume, audio level and settings, RF health, battery status, and more via LinkDesk software. Variants include UHF (470608 MHz and 630698 MHz) or 1G4 (13501400 MHz and 14351525 MHz). Spectera SEK body packs feature an impedance matching high power headphone