This is a two component system: A: Resin an B: HardnerThis comes with both Parts A & BThis comes with both Parts A & B This is used to soak 1 layers of 36 oz fiberglass matting. Unit will cover approx. 80sq ft. This is soak into the fiberglass and improves upon it structural integrity making it stronger. You can use this alone as well for a primer/bond coat for multi surfaces such as wood and concrete ETC for waterproofing.<