Access Control Intercom, Open Voice, Door Station Height 6 In, Door Station Width 4 3/4 In, Door Station Depth 1 3/4 In, Master Depth 1 9/16 In, Master Height 8 1/4 In, Master Width 3 1/4 In, Distance 300 Ft) @ 18AW, Distance 150 Ft) @ 22AW, Talk Channel Output 5 W, Listen Channel Output 5 W, Wiring Conductors 2, Wire Type Unshielded, Power Source 15 VDC, Voltage 120 VAC