J-B Weld Muffler Patch is reinforced with fiberglass and a special one-component epoxy compound that hardens when exposed to heat. On contact with a heat source, this product will polymerize and form a solid, permanent stain on the underlying surface. Epoxy coated fiberglass casingResists up to 315 ° CHeat-hardens in 20 minutesHardens like steelIdeal for muffler repair
