3M™ Marine Adhesive Sealant Fast Cure 4200FC is a one-component, medium-strength, moisture-curing, gap-filling polyurethane that delivers strong, flexible bonds to aluminum, wood, gelcoat and fiberglass. It forms watertight, weather-resistant seals above and below the waterline. In addition, its flexibility allows for dissipation of stress caused by shock, vibration, swelling or shrinking. - 3M marine adhesive/sealant Fast Cure 4200FC white bonds and seals fiberglass, gel coat and wood. Ideal for rub-rails, stern-joints, deck and through-hull fittings and access plates. Medium strength allows for disassembly.