Material & Feature SUMITUBE F32 is a flexible, flame retardant, irradiated crosslinked, heat-shrinkable, modified polyolefin tubing that is recognized by Underwrtiers Laboratories (UL) and Canadian Standards Association (CSA), is a high-reliability products. Sumitube F32 represents the excellent balance of property for general purpose use such as insulation or jacketing of wire harnesses, insulation of wire terminals, capsule of electronic components, wire marking, color coding where flame retardance or UL and CSA recognition should be needed.