Electronics-Salon Balanced Four Stereo Audio Signal Input Selector Relay Module. 4 Balanced Stereo Audio Signal Input Selector Relay Module. Operating voltage: 8.5 ~ 15.5VDC, recommend 12VDC . Operating current: 15mA (at 12VDC). Rotary switch wire length 300 mm (11.8 inch). Size: 115mm(L) x 50mm(W) x 16mm(H), (4.53 x 1.97 x 0.63 inch).