5mm, 4mm, & 6mm heat shrink tubing for electrical insulation, wire bundling, and protection. Available in multiple colors and sizes. Shop DigiKey's large in-stock selection of Heat Shrink Tubing. View inventory, pricing and order now for same day shipping!The fiber optic drop cable protection box is a case to put in a cable with a thermal protection tube after hot melting, so that the splice spot can get a better protection relative to the cold welding. The hot one can improve the performance of connector, increasing the effective connection rate to. Clear sleeve make it easy to detect splice before shrinkage. The fiber optic heat shrink tubes is tight and the metal support maintains its strength to prevent the fiber from breaking at the splice.