1. WT236 is a 2.36inch adjustable wall thimble and should be used when running the 2.36inch pipe horizontally through a combustible wall. 3. wall thimble made of high-quality stainless steel, features the highest pressure rating in the industry. It has a and is . 2.It's very easy to install. It has simple gasketed connection, no sealant and tools are needed to install. 4.The stainless steel wall thimble has new fusion welded pipe seams for a smoother finish and better fit.