This SAE Standard specifies the essential dimensional features of R, b, and M rectangular piston ring types. Dimensional tables 8 and 9 offer the choice of two radial wall thicknesses: a. radial wall thickness "regular" (table 8); b. radial wall thickness "D/22" (table 9). The requirements of this document apply to rectangular rings for reciprocating internal combustion piston engines up to and including 200 mm diameter. They may also be used for piston rings of compressors working under similar conditions.