Proflex Dryer Vent Kit, 4 in Collar, 3 Pieces, Includes: (1) 4 in X 8 ft Proflex Transition Duct, (1) Plastic Connector and (1) Optional Plastic Extension, Polypropylene, White, UL Listed, UL94 V0, Used to Prevent The Duct From being crushed and improves airflow