Glass Fibre Filler (Fibre Tough) is a high quality fibre reinforced polyester putty designed for trade use. Glass Fibre Filler is dependable and easy to use and is formulated to bridge holes up to 50mm in diameter in rusted metal panels in motor vehicles, caravans, trailers and boats and in guttering. Glass Fibre Filler is fast setting, exhibits maximum adhesion to metal with excellent resistance to shrinkage and is waterproof when fully cured.