Hart & Cooley Butterfly Damper, Round, 8 Inch, For Use With: No 16 Diffuser, 9-1/2 Inch OD Diameter, 4-11/16 Inch Depth, Cold Rolled Steel, Golden Sand Enamel, Includes: Removable Control Knob
- Controls air volume evenly over entire diffuser
- Removable knob operator for adjustment from closed to fully open
- Knob permits diffuser to be held in position while attaching face screws
