Zone Dampers2-wire installation is dependable and simple; easy slip-in design. Solid construction with extruded aluminum frame and blades. Fail-safe, normally open operation. 24V spring-return motor. Quiet parallel blade design with fewer blades. Mount on side or bottom of duct.Zone Damper, Square Damper, Voltage 24 AC, Height 20 In, Width 24 In, Depth 4 In, Output Amps .32A, Connection 2 Wires, Rotation Angle 90 Deg, Timing (Sec) 30, Ambient Temp Range 40F-140F, Power Method 24 Volts, Application Controls Air Flow In Heating And Cooling Systems, For Use With Forced Air Zoning Control Panels