3M™ Short Strand Reinforced Filler, 01160, is intended to fill gaps up to a 1/2 inch (1.27 cm) wide. It can be used in conjunction with fibreglass tape, cloth or mat to repair and rebuild rusted out metal and damaged fibreglass materials. The filler is reinforced with short-strand fibreglass to create a waterproof repair. Marson® Mar-Glass® polyester filler is reinforced with short-strand fiberglass to create waterproof repairs that are twice the strength of ordinary body fillers.