A gasket is a mechanical seal between two objects, usually used to prevent pressure, corrosion, and leakage of natural expansion and contraction of pipelines between two objects. The gasket can be used to fill irregularities. Gaskets are usually made of sheet materials such as pad, rubber, silicone rubber, metal, cork, felt, neoprene, nitrile rubber, glass fiber, or plastic polymers (such as Teflon). Gaskets for specific applications may contain asbestos.