Prevent drafts with our Plastic Dryer Vent Draft Blocker. When your clothes dryer is in use, the exhaust opens the built-in damper. Gravity keeps it closed when you're not drying laundry. Durable plastic construction was a melting point of 325 degrees F. Damper unit comes fully assembled, and installs to the clothes dryer duct and vent pipe. Deflecto was founded on innovative, problem solving products. For over a half century, we have built a tradition of discovering and meeting needs with invention and dependable manufacturing. Today, Deflecto is the world's largest chair mat, bicycle reflector and dryer venting manufacturer and a global leader in sign and literature holders, office workspace accessories and other air distribution products.