3:1 Shrink Ratio: Shrink tubing will become one-third of its original size when heat is applied, more resistant to stretching and vibration than regular heat shrink, and has more tensile strength Dual Wall Shrink Tube: Reliable and long-protected adhesive-lined heat shrink tubing consisting of two layers, waterproof and sealed Flame-retardant and Low Smoke: Electrical shrink wrap tubing is made of polyolefin and an inner layer consists of a meltable adhesive, that withstands temperatures of -67 to 257 degrees Fahrenheit (-55 to 125 degrees Celsius) Easy to Use: Simply slide heat shrink tube over your connection point and apply heat. Make professional insulated connections in seconds Widely used: Heat shrink tubing is mainly used for electrical insulation of wires, solder joints, connectors, and terminals, heat shrink can also be used to prevent damage, strain relief, bundling wires, etc. The size of this heat shrink tubing is marked by its round inner diameter (diameter when round) and is shipped in a flattened state (flat width). For example, a heat shrink tubing labeled as “2 inches (50mm) diameter” will have a flat width of approximately 3 inches (75mm). Please select the appropriate size based on the round inner diameter.