Product Specifications:  Control Unit Features System "Brain"  Loud electronic buzzer  Reset button  Lock-out circuitry  Accommodates a total of 8 Remote Units of any style (Mix/Match)  Durable spring-loaded terminals for quick, reliable hook-up  1/4" audio output jack included for connection to your sound reinforcement (PA) system, if desired  Plug-in wall-wart power supply included  No computer or software required  Durable construction  Size: 6"W x 8"L x 2.5"H