Kit includes: One 4" x 8' UL 2158A listed and marked semi-rigid aluminum duct. Two attached all metal heavy duty elbows. Two 4" metal galvanized worm gear clamps. Duct meets and exceeds all dryer manufacturers instructions and requirements. 35% thicker than our standard non UL duct and aluminum ducts is totally noncombustible. Two metal elbows are flame resistant for a safe and long lasting connection. Designed to achieve tight 0 to 90 degree turns which saves space while still maximizing airflow, crush resistant.