Piston rings kit compatible with 38 to 39mm bore engines. Designed for use with models including XC50, XC50D, XC50H, BX50, CE50, NS50F, XF50, XF50D, XF50L, YN50F, BX50N, and CE50D. This set includes piston rings that help maintain proper compression and oil control in small displacement motorcycle engines. Suitable for routine maintenance or engine rebuilds. Compatibility Disclaimer: This is an aftermarket replacement part. Any brand names or model designations mentioned are used solely for the purpose of demonstrating compatibility.