We need Heat Shrink Tubing in our daily life. Heat shrink tubing (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.
Besides, it contain other features. The  Heat Shrink Tubing is placed over the connection to be protected and then heated with an oven, hot air gun or similar tool. Convenient, but less effective, methods for shrinking the tube include a soldering iron (held in close proximity, but not touching the tube) or the heat from a lighter. These processes cause the tubing to contract as far as one sixth of its original diameter (dependent on the heat shrink, 2:1 is the most common), providing a snug fit over irregularly shaped joints. This provides good electrical insulation, protection from dust, solvents and other foreign materials, as well as strain relief. If overheated, heat shrink tubing from Heat shrink tubing suppliers can melt, scorch or catch fire like any other plastic. Some types of heat shrink contain a layer of thermoplastic adhesive on the inside to help provide a good seal and better adhesion, while others rely on friction from the closely conforming materials. Heating plain, non-adhesive shrink tube to very near the melting point may allow it to fuse to the underlying material as well. One application that has used this product in large quantities since the early 1970s is the covering of fibreglass helical antennas used extensively for 27 MHz CB Radio. Many millions of these antennas have been coated with this versatile plastic shrink tube product.