Blocks out air and locks in freshness to extend the sealing power of Flex Paste, with no waste. Penetrates deep to seal out air, water, and moisture. Once dry, it turns into a strong, flexible, watertight, rubberized barrier. Can be applied underwater, and it even dries underwater. Super thick rubber paste clings to the surface and instantly fills large gaps, cracks, and holes. Once fully cured, it can be painted any color. Helps prevent rust and corrosion, and it is UV resistant.