- A gasket in the form of a ring with a circular cross section, typically made of pliable material, used to seal connections in pipes, tubes, etc
- An O-ring, also known as a packing, or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a disc-shaped cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.
- (O-Rings) are generally used as dynamic seals for shafts and are available in many different sizes and materials.
- a gasket consisting of a flat ring of rubber or plastic; used to seal a joint against high pressure