Heat-shrink tubing is plastic tubing that can shrink when heated. It is used to insulate wires and to protect solid wire conductors, joints, connections and terminals. It is often used in electrical engineering to protect wires from abrasion.
Heat-shrink tubing is generally made from nylon or polyolefin. Polyolefin shrinks only in its diameter and can shrink to between one-half and one-sixth of its original size. Different sizes and types are made, each with varying chemical makeups that suit each type of tubing for an individual task. Heat-shrink tubing is rated according to its expansion ratio and its rate of recovery.