Studio Technologies 31211 Backup Microphone Output Card Kit for Models 210, 211, 220, 230, and 233Allows technician to create an audio output that automatically switches between the main output signal and the microphone input connection. Used to provide an automatic "fail over" connection for specialized on air broadcast applications. Installs in back panel spare connector location in Models 210,220, 230, and 233 Announcer's Consoles. Card features 3 pin male XLR type connector and high reliability sealed electro mechanical relay. Kit includes