SD 8" Round Damper - Power Open/Power Close - 24VAC, Efficient, Durable, 5-Year Warranty -Normally Same Day Shipping-

Quiet, sturdy and reliable. Very happy with this purchase, only complaint, and not really a complaint, just an observation, is the action is slow to open and close. It takes about a minute to change states from open/close or close/open. GREAT PRODUCT! PS it even has foam gasket on damper to ensure as tight a seal as possible.