Engine Compatibility This piston ring set is primarily used across various small 4-stroke engines manufactured by Kawasaki (commonly found on lawn mowers, zero-turns, and outdoor power equipment from brands like Cub Cadet, John Deere, Exmark, and Toro): Engine Series: Compatible with select models in the FH, FC, FR, FS, and FX series engines. Superseded/Cross-Reference Numbers: In some parts catalogs, it may cross-reference or supersede to parts such as Cub Cadet part number