this box came with about 6 different sizes. They are thicker than ones i bought in auto parts store and better quality. I used a lighter to shrink the tube over the wire and given the thickness of the tube, it required a few passes for secure shrinkage and the glue to work. Be careful not to overheat as tube can wear thin and compromise the insulation. Better to pass the flame over the tubing 3-4 times, examine and pass flame again if more shrinkage is needed. Great quality product that I enjoyed using.