This specification covers flexible and semirigid crosslinked polyolefin heat-shrinkable tubing used for electrical insulating purposes. It is in its expanded form and will shrink to its extruded diameter when heated. The tubing has been classified into four types according to flame retardancy, flexibility, opaqueness, and secant modulus: Type I, Type II, Type III, and Type IV. The compound used in the manufacture of heat-shrinkable tubing shall be modified polyolefin resin, and the finished compound shall be free of all foreign matter other than intended formulation additives as appropriate. The tubing shall be extruded, cross-linked, and then expanded to the required dimensions. The following chemical properties of the material shall be determined: corrosion, fluid resistance, flammability, and water absorption. Physical properties of tubing like restricted shrinkage, dielectric strength, heat shock, low-temperature flexibility, tensile strength, elongation, heat resistance, color, color stability, specific gravity, volume resistivity, secant modulus, copper contact corrosion, and copper stability shall be determined.