Dicore Heat shrink tubing (www.dicoretubing.com) (or, commonly, heat shrink) is a tube which shrinks in diameter when heated. Its diameter and thickness can vary, and there are three main categories, thin-wall, medium-wall and thick-wall tube. It is rated by its expansion ratio, a comparative of the differences in expansion and recovery rate. Heat shrink is used to insulate wires offering abrasion resistance and environmental protection for conductors, connections, joints and terminals in electrical engineering. It can also be used to repair wires or bundle them together, to protect wires or small parts from minor abrasion, and to create cable entry seals, offering environmental sealing protection between bulkheads and adding sealability to electrical junction boxes.