Riverbyland Iron On Biker Patch For Jackets Skull Engine Fabric Patches Size: 25x22 cm Use: iron on patches. The back hot melt adhesive is pro-environment and non toxic. Suggestion: sew on after iron makes patches more firmly. These biker patches are great to patch holes or decorate bags, caps, backpacks and more. Washing: easy to use, easy to clean. Gentle cycle or hand washing is best. Do not use hot water.