Made of Polyolefin. The shrinkable ratio is 2:1. This heat shrink tubing is measured by the inner diameter. IT IS NOT MEASURED FLAT. Tubes shrink to fit over cable and can be used for electrical insulation, strain relief, cable bonding, color-coding, wire marking, corrosion protection, solder insulation, wire bundling, and more. Used for auto, marine, plane, home, industrial, computer and much more.