Gardner Bender HST-375 3/8-Inch by 4-Inch Heat Shrink Tubing, 3-Pack. Size:4 Inch | Style:⅜ Inch Diameter | Color:Black | Material Polyolefin, Rubber. Polyolefin shrink tubing shrinks under heat application to insulate wiring up to half its diameter. Thin wall heat-shrink tubing is constructed from durable, flame-retardant black polyolefin which is resistant to both solvents and fluids making it ideal for cable insulation, repair, marking or bundling. Heat shrink not only provides superior mechanical, abrasion and moisture protection but also strengthens connections and provides a comfortable gripping surface. As a result, professional and DIY multi-purpose uses include repairing cords (ranging from large appliance cords to small electronic cables that show wear at pull-out), covering tool and sporting equipment handles, and sealing rope for neat, unravel resistant ends. Finally, tubing capably resists common fluids and solvents. Upon heating to 120⁰ C (250⁰ F) the tubing begins to shrink but will not drip, crack or flow and is self-extinguishing within 30 seconds. Meets UL 224, 125⁰ C: CSA C22.2 No3 198.1, 125⁰ C; MIL-DTL-23053/5, Class 1 and 2, AMS 3636 and 3637; DEF STAN 59-79, Issue 3 Type 2a. Continuous operating temperature: -55⁰ C (-67⁰ F) to 135⁰ C (275⁰ F). Shrink temperature: 120⁰ C (250⁰ F) to 250⁰ C (480⁰ F). 600 V/Mil Dielectric strength.