This is a pair of replacement O.S. Engines Piston Pin Retainers, and are intended for use with the O.S. O.S. 91HZ-PS, and 91HZ F3C Helicopter Engines, and the O.S. 75AX, and FS-110-a Engines.
NOTE: This part may be compatible with other O.S. engines. Please check your owner's manual and cross reference the part number to verify that this is the correct part for your engine.