Bondo glass reinforced filler makes an excellent foundation for hole, dent and rust-out repairs without the need for backing strips, cloths and resins. It contains short, interlocking fiberglass strands and fibers that make it twice as strong as regular body filler. It is also slightly thicker and provides a fast drying time, making the filler less messy on vertical surfaces like car doors.Fiberglass strands and fibers make it twice as strong as regular body fillerCovers small (up to 1/2 in) holes without the need for backing strips, fiberglass resin or clothExcellent as a foundation for hole, dent and rust-out repairCan be paired with body filler and glaze for complete repairsSandable in as little as 20 mins for quick repairsCompatible with most paintsWaterproof formula works for cars and boats