The type of heat shrink tubing you need for your project depends on the item that needs to be protected or insulated. There are two key types of heat shrink tubing to select depending on weather moisture protection is required or not.

Single Wall Tubing
Single wall tubing is very flexible and suitable for many applications. Made of polyolefin, it is commonly used for protection of enclosed wires and cables. This thin tubing works primarily as an electrical insulator and also for wire identification.
There are two standard shrink ratios: 2:1 and 3:1. The shrink ratio determines how much the diameter of the tubing shrinks when heated to ensure a proper fit. Single wall tubing is available in several colors on various size spools, or in 4-foot-long pieces. It also has excellent flexibility and high flame-resistance, as well as a low shrink temperature of 90ºC .