Heat-shrink tubing
（重定向自Heatshrink）
Heat shrink tubing (or, commonly, heat shrink or heatshrink) is a shrinkable plastic tube used to insulate wires, providing abrasion resistance and environmental protection for stranded and solid wire conductors, connections, joints and terminals in electrical engineering. It can also be used to repair the insulation on wires or to bundle them together, to protect wires or small parts from minor abrasion, and to create cable entry seals, offering environmental sealing protection. Heat shrink tubing is ordinarily made of nylon or polyolefin, which shrinks radially when heated (but not longitudinally), to between one-half and one-sixth of its diameter.