Niles SPK1 Black (FG00240) Speaker Level A-B Switcher Replaces manually operated A-B switches Audio power handling: 600W per channel SPK-1 is activated by 12Volt DC signal (100mA minimum) Requires 12Volt DC adapter to trigger SPK-1 from the switched outlet of a receiver or preamp, can also be triggered by the 12Volt output of a Niles APC-2, AC-3, AVS-2, SAS-1 or RFS-1 12Volt control output for activating other Niles devices such as APC-2, AC-3, AVS-2, SAS-1 or RFS-1