Continental Fan Manufacturing Back Draft Dampers. Foam gasket prevents air leakage. Back Draft Damper blocks and controls draft. 4" thru 16" Duct sizes available.
FAMCO Back Draft Damper in Connecting Sleeve. Opens with Normal Air Flow - Gravity Close. No Springs or Hinges. 4" thru 20" Duct
FAMCO Reversible Back Draft Butterfly Damper with Wall Vent. Reversible Air Flow direction - Air Intake or Exhaust. Galvanized or Aluminum Vent. 4" thru 12" Duct.