3M Dynatron Dyna-Hair Long Strand body filler repairs splits, cracks and holes in all kinds of surfaces, including wood, fiberglass, aluminum and bare or galvanized steel. Reinforced with long fiberglass strands, this waterproof filler offers additional versatility to any automotive repair. Dynatron Dyna Hair reinforced body filler provides a balance of performance and economy when repairing splits, cracks or rust holes in automotive bodies, boats, etc. Reinforced with long strand fiberglass, this filler creates waterproof repairs that are twice the strength of ordinary body fillers. Our two component polyester compound applies easily and creates a smooth, professional quality repair. This filler is produced with the highest quality resins, talc and microspheres. Dynalite has become an industry standard because it combines ease of use, faster working properties and top notch results.