Inter-M 16 zone, 100v line speaker selector 16 Zone 100V Line Speaker Selector Make certain that speakers and input sources are properly connected before switching the unit on. Keep volume levels turned down before switching on. Features 16 ZONE SPEAKER SELECTOR (ALL CALL, GROUP 1, GROUP 2, CH1~16) 19 push type selector switches are provided to enable you to select 16 zone speakers individually or totally. EASY CONFIRMING You can confirm selected zone and the operating mode of system by using label holder and indicating LED on the front panel. ALL SWITCH You can select all zone speakers use by one switch. GROUP 1, GROUP 2 SWITCH You can select group 1 speakers(CH1~8) or Group 2(CH9~16) by individual group switches.