Dual wall heat shrink tubing with the internal adhesive layer. It is 3:1 shrink ratio tubing, which allows it to be used in significantly more applications compared to 2:1 shrink ratio tubing. When heat is applied, shrink tubing recovers and the internal adhesive layer melts. A small fillet of clear adhesive (about 1 mm wide) becomes visible at the end of the heated tubing. When cooled down it forms a rigid seal.