An O-ring is a mechanical gasket in the shape of a torus or donut; it is a loop of elastomer or other material with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.

An O-ring is a mechanical gasket in the shape of a torus or donut; it is a loop of elastomer or other material with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.