O-ring

Some small o-rings

An o-ring is a rubber gasket with a round cross-section, and is usually used to create an airtight seal around moving parts, such as pistons and bolts. O-rings are cheap and come in a wide range of sizes. However they need to be mounted in a precisely machined groove for most applications, and a lathe is usually needed to achieve this, so they are not always a viable option.

An o-ring seal, when done correctly, can hold thousands of psi. This article is a stub. You can help by expanding it