Model No: IEM-Assist-8-Extend UPC: 692868398810 Brand: VocoPro Country of Origin: CN Best sounding assistive 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 26 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) Battery: Built-in Lithium Ion 3.7v 1380mAh (quantity 2 per body pack receiver)