Bondo Body filler is the original formula which has been helping DIYers for years to repair the toughest dents and dings.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 stronger than 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.