Tundra brand polyethylene pipe Insulation is a flexible and easy-to-apply tubing product available in semi-slit and self-sealing styles. It is packaged in cartons that feature the copper tube sizes in bold color-coded print. The Self-Sealing version has yellow self-seal release liner that is both easy to see and peel. Tundra brand polyethylene pipe Insulation is sold in all the common sizes required for home plumbing systems, including special fittings for tees and 90 deg elbows. This chemically inert pipe insulation has a closed-cell structure that allows it to function as an efficient insulator.