Best for repair of fiberglass and metal surfaces. Will rebuild rotted-out areas on fenders, body sections and rocker panels. Also used for forming special customized shapes. Kit #370 contains 1 qt polyester resin, 11 cc liquid hardener, 6 sq-ft fiberglass mat, 3 in x 5 ft fiberglass tape and instructions. Kit #637 contains 8 fl-oz resin, 1/4 oz liquid hardener, 3 sq-ft fiberglass cloth, mixing stick, plastic spreader, mixing tray and instructions.