The 3M black adhesive-lined polyolefin heat shrink flexible polyolefin tubing is sold 2 pieces per case and is another quality product from 3M. Has a dielectric strength of 800 v/mil. This product starts out with an inner diameter of 2 in and after heat is applied it reduces in size to 1 in. Along with other changes the wall thickness also changes when this product is used. After use the wall thickness is 0.06 in. The overall length measures 48 in.