SAFE AIR DOWCO-Heavy duty industrial Isolation Round Damper model No HTR-1 needed. We are in need of 4 of this type of damper. Please refer the following website for reference. www dot safeair-dowco dot com. The route is PRODUCT-INDUSTRIAL DAMPER-Heavy Duty Round Dampers-Model HTR-1 Isolation Damper. It will not be nessary for this bran Show More...