SoundPlus® 4-channel Infrared Receiver
The WIR RX22-4N is a four-channel selectable, infrared receiver compatible with transmitters operating on the 2.3/2.8/3.3/3.8 MHz bandwidth. Dual infrared detectors maximize sensitivity and operating range. Range of up to 28,000 square feet (2,600 square meters) in single-channel mode when used with a Williams Sound WIR TX925 or WIR TX90 infrared system. Comfortable, body-pack design features convenient channel selector and easy-to-use on/off volume control. The RX22-4N can be used with mono or stereo headphones, earphones or a neckloop (lanyard included).
More information: https://www.williamssound.com/catalog/wir-rx22-4n