Commax DR-4US is an expansion audio port for 4 subscribers for DR-nUM
Communication line: 3 common wires + 1 from each DP-SS
Metal buttons, backlighting of the nameplate. Mortise fastening
Power supply: DC 12 V
Dimensions of the outer part (B * W * D): 315 * 130 * 10 mm. Dimensions of the mortise part (B * W * D): 305 * 122 * 37 mm.