Laboratory stoppers are truncated, cylindrical or conical pieces that are used to plug, close and/or seal labware. They are usually made of rubber, neoprene, plastic, or glass. Product categories include one, two and three-hole lab stoppers; penny head and cylindrical cap; and handle stoppers. Lab stoppers may be solid or hollow, and disposable or reusable. Typically, reusable products are sterilized in an autoclave.