These heavy gauge Plated Steel quadrants are designed with excellent handle action as well as quick wing nut adjustment and locking of the damper. The frame is marked to show the exact position of the damper. For use on square or round ducts.
Duro Dyne Quadrant Damper Set, Accessory Type: Quadrant Damper Set, For Use with: 30 in Damper, 1/2 in, Domestic