300pcs organized kit of dual color, pre-cut to convenient sizes and various dimensions | 3:1 shrink ratio allows you to use this tubing in more situations than the usual 2:1 ratio tubing and results in a snug fit | The internal adhesive layer is super powerful and melts easily forming a watertight seal that holds the wires together | Dual-wall safe heat shrink tubing is waterproof and corrosion resistant. Best for electrical insulation, wire bundling, cable joints protection and wire repair | Easy to use. If you don't have a heat gun, a hairdryer or a lighter would also work