VC-4-1 Noritz Stainless Steel 4" Outdoor Vent Cap The VC-4-1 4" vent cap is made of high temperature stainless steel to help protect your outdoor tankless water heater while providing a clean professional look. As part of the N-Vent series, this product is UL approved category III venting, known for easy installation and forming tight seals. Vent Cap: Prevent debris, critters and water from entering the vent pipe of your outdoor tankless water heater to ensure proper functionality and a safe and efficient system.High temperature rated stainless steelProtects vent systemUnique gasket enables tight sealEasy to install Quick-Snap connectionSuperior design