Perfect for sealing spark plug wires to boots at each end forming a water-tight weatherproof seal. With a 3 to 1 shrink ratio, shrink tubes can be used to bundle wires as an alternative to tape or plastic ties. 3:1 shrink ratio Offers a clean & professional under hood look Easy to install using a heat gun 25 tubes to a package Four colors to choose from DO NOT apply directly to exhaust components.