Vent Termination Hood is a must for Eccotemp 40HI series models in combination with a backflow preventer to prevent freezing air from coming back through the vent stack. Features the highest pressure rating in the industry and is the only metallic special gas vent you can cut to length on site. Has a simple gasket connection with no sealant needed. Compatible with all types of Z-Flex Z- Vent. Made of AL-294C Stainless Steel