HEATSHRINK TUBING ASSORTMENT 9.5MM - 19MM DIA.. Narva heatshrink is manufactured using flame-retardant/self-extinguishing polyolefin making it suitable for most automotive applications. Dual Wall heatshrink combines an increased wall thickness with adhesive to create an increased level of strain reliefnot achievable with standard heatshrink tubing. The use of adhesive also creates a waterproof seal.