WT4-H-8-1 Noritz Stainless Steel 4" Adjustable Wall Thimble with TerminationMade of high temperature rated stainless steel, the WT4-H-8-1 4" diameter wall thimble is easy to install and helps keep your home safe. With adjustable venting, built in termination and a superior design, the WT4-H-8-1 is also versatile, and can span length from 4.1"-7.8". As part of the N-Vent series, this product is UL approved category III venting, and is an integral part of the quick-snap connection system, known for easy installation and forming tight seals. Wall Thimble: Keep your installation up to code, and your home safe with a stainless steel wall thimble that spans the width of your wall and keeps a safe clearance between the vent pipe and building materials. As part of the Noritz N-Vent series, this piece easy to install and known for its tight seals, as well as approved for tankless and boiler stainless steel exhaust installations, enabling you to know you've made the right choice in both form and function.High temperature rated stainless steelEasy to install Quick-snap connectionUnique gasket enables tight seal