What is cellular rubber? A waterproof and flexible foam rubber | NDS-Seals
Rubber-Cal Rubber-Cal Closed Cell Rubber Neoprene- 1/16-in Thick x 39-in x 78-in in the Washers, Gaskets & Bonnet Packing department at Lowes.com
What are Expanded Rubber and Closed Cell Rubber? - Stockwell Elastomerics
Amazon.com : XCEL Extra Large Marine Roll, Closed Cell Rubber with Adhesive, Size 60" x 16" x 1/2", Easy Cut Material, Lightweight, Water and Weather Resistant, Great for Crafts and DIY Projects