20Bx Lrg Rnd Tube Patch 11-003 Large Round Feather-Edge Tube Patch Repair Units. These tube repair units, designed principally for use on inner tubes, are twice as strong as the tube being repaired and have a feather-edge design to prevent chaffing. When repairing inner tubes, buttonhole the ends of the injury and select a repair unit at least twice as large as the injury being repaired. Features: Designed for chemical vulcanization. Black vulcanizing gum, white poly backing. Made in the USA. Specifications: Patch Diameter: 3.125" (79 mm). Patches Per Box: 20.