43mm Cylinder Piston Ring Kits For 545 545XP 550 550XP 550XPG 577764706 577764708 577764707 This piston ring kit is designed for use with specified engine models.It includes a set of machined rings sized to fit a 43mm cylinder bore.The components are engineered to maintain proper compression and oil control within the engine cylinder.Each kit contains the necessary piston rings for replacement during engine rebuild or maintenance.Compatibility is limited to the listed model numbers.Installation requires standard mechanical tools and knowledge of small engine assembly procedures.