This Comtek wireless monitoring system allows for complete audio monitoring for up to 5 people on set. All audio that your sound person hears and records is transmitted directly to the Comtek receivers and straight to your director, producers and clients. Set contains M-216 P7 Transmitter, one PR-216 Option P7 Receiver, and four PR-216 Beltpack IFB receivers which all run off 9-volt batteries. Rental comes with one transmitter, five receivers, and five sets of headphones.