This is a USC24035 Duraglas Fiber Filled Filler. Is the original fiberglass reinforced automotive body repair filler. Formulated with short-strand fiberglass fibers. Duraglas provides ultimate strength & durability on rust-outs, holes, tears & cracks. Ideal for use on metal & fiberglass panels #1 short-strand fiberglass filled body filler/reinforced for superior strength. Use with fiberglass cloth for large repairs. Rust-proof, weather-proof.