A circular, single or multiplier item, metallic or nonmetallic in composition, designed to be fitted in a circumferential groove in a piston and to spring outward against the cylinder wall to function as a seal or wiper. It is supplied in various cross-sectional shapes and is cut through at one point to allow for installation in the piston ring groove. It may include an expander. Excludes packing, preformed; retainer, oil seal; retainer, packing; ring, retaining; ring wiper; and seal ring, metal.