Dynatron Dyna-Glass Short Strand reinforced body filler creates waterproof repairs that are twice the strength of ordinary body fillers. The filler is designed to be used as a reinforcement material where a stronger filler is needed when repairing or filling larger gaps in auto body, marine, industrial and architectural surfaces.Reinforced with Short Fiberglass StrandsDynatron Dyna-Glass Short Strand body filler is reinforced with short-strand fiberglass to create waterproof repairs that are strong and durable. It can be used to bridge a 1/2 inch hole, and can also be used in conjunction with fiberglass tape, cloth or mat to repair and rebuild rusted-out metal or damaged fiberglass materials. 3M Dyna-Glass Filler offers excellent sag resistance, high build and gap spanning characteristics.