3:1 SHRINK RATIO - Recovers to 1/3 of its original diameter, and makes a tight seal. Eliminates the problem of 2:1 tubing not shrinking tight enough. GLUE INSIDE - When heat is applied, adhesive comes out and seals the connection, creating waterproof and long-lasting insulation. VARIETY OF SIZES - We have included 7 most commonly used diameters ranging from 3/32" to 3/4". Shrink tubing is precut to 3.5 inches. EASY TO USE - Simply slide heat shrink tube over your connection point and apply heat. Professional connections made in seconds. DUAL WALL TUBING - Outer wall provides abrasion resistance. Inner wall creates waterproof seal and strain relief.