Builders Best V230 Flexible Pipe PRO Plain Ends 4inch X 8ft.The V230 PRO plain ends is a Class 0 Duct used as supply, return or exhaust. It solves the need for a stronger than average general purpose venting duct. Our factory crimp ensures smooth connections. Designed for low and medium operating pressures Made of non combustible corrugated aluminum Plain ends Ships compressed to 24 Same strength as V330 Thicker wall than V220