The DA-1AS is a Two-wire Door System Set containing: DA-1DS, DA-1MD & PT-1211C: DA-1DS is a silver door station that connects via two wires to a master DA-1MD. System power is the PT-1211C. The DA-1DS features a 12V AC output for door strike connection, call button and illuminated directory. The master handset DA-1MD features a call tone volume control, handset for communication and button for door release.