Leak preventers are devices used to stop the flow of liquids or gases from escaping a container. They can be made of a variety of materials, such as washers, gaskets, and sealants. Washers are thin plates with a hole in the middle, usually made of metal or rubber, that are used to distribute the pressure of a threaded fastener. Gaskets are mechanical seals that are used to fill the space between two objects, preventing leakage. Sealants are substances used to block the passage of fluids through the joints or seams of two surfaces. All of these components work together to create a tight seal that prevents leaks.