Heat shrink tubing is a plastic tube that shrinks to between one fifth and one sixth of its original size when heat is applied. Common materials used are nylon and polyolefin. Raw heat shrink tubing is fitted over wiring, then an heat gun is used to raise the temperature and cause the tubing to shrink by 15-50% depending on the material. Heat shrink tubing is used to insulate and protect electrical wires and connections from damage. The Raychem Corporation, located in California, was an early innovator in heat shrink tubing and the Tyco Electronics brand continues production today under the Raychem name.