Fiberglass Resin with Hardener - This is a heavy bodied formula that will not run or sag and cures to a non-tacky surface. Easily saturates fiberglass mat and cloth. Cured repairs can be filed, sanded or drilled, are Impact resistant and waterproof. Use with Fiberglass Cloth (10523) or Mat (10522) to rebuild and repair. Liquid hardener included.