3M Heat Shrink Tubing SMS is a dual wall tubing that is specially designed for automotive wire harnesses. This tubing has a 4:1 shrink ratio and semi rigid polyolefin construction with an internal layer of thermoplastic adhesive offers moisture seal protection.3M Heat Shrink Tubing SMS is color coded for quick and easy identification of the wire. This flame retardant tubing is puncture resistant and offers good strain relief as well as mechanical protection. It is ideal for insulation of automotive, RV, truck, tractor, heavy equipment and marine wire splices, in line components, fusible links and terminals. It withstands temperatures of 67 to 230 degrees F ( 55 to 110 degrees C).