3M CAULKING 4000 UV CARTRIDGE FAST CURE FLEX High quality cosmetic sealant cures to form a firm, rubbery, water-tight seal. Superior UV resistance. Very low odor. Resistant to weathering, saltwater and stresses caused by joint movement. Remains flexible. Seals between mechanically fastened joints on wood, fiberglass, metal and most plastics above and below the waterline. Applications include sealing deck to hull joints, thru-hull fittings, window and door frames, deck hardware, transducers, transoms, navigation lights, hatches and porthole frames.