This kit fit`s all AR50s. The new bore size is 53mm giving an impressive 91.8cc when standard they are 49cc
the kit is made in taiwan by a well known piston manufacturer whose products end up in many different branded boxes
the top ring is a standard keystone type, which is much more robust than the dykes type that is found on some other kits, the overall quality is very good, set it up right and you will get good power and good reliability.