Leakage preventers are devices used to stop the flow of liquids or gases from escaping a system. GASKET is a mechanical seal that fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. SEALANT is a substance used to block the passage of fluids through the surface or joints or openings in materials. Together, GASKET and SEALANT are used as leakage preventers to ensure that no liquids or gases escape the system.