12 x 8 inch louver to 8 inch round galvanized metal

The ABV damper is an automatic balancing damper that maintains a constant airflow volume in HVAC applications. The engineered damper blade and stainless steel spring are laboratory calibrated to automatically adjust to varying pressures—using physics not electricity—giving the ABV damper true pressure independence.
The ABV damper is a reversible product—it can be used for exhaust or supply applications.
However, the ABV damper is air flow dependent and the direction of airflow through the product is critical for proper operation.
Classified by UL to UL 2403 for heat release rate and smoke optical density.
Suitable for application in temperature from 25 to 150F (-4 to 65C).