Best sounding assisted listening system on the market with True Stereo equipped with two digital chips per transmitter and receiver. Digitally encrypted to keep content private and secure 24 Bit Digital, Dual Frequency (True Stereo) Transmitter and Receiver Up to 9 sets are designed to work together without interference. Operating in the 900MHz range, free of TV broadcast and Wi-Fi interference Rugged, rechargeable all metal body-pack Receiver will work with most headphones (each receiver Includes IE-9 In-Ear Headphones)