Almost every Mini built prior to the dual circuit system uses a .70" bore master cylinder. This kit fits them all. The original size in the '59-'64 Mini was .75" but as most of these cylinders have been replaced with the .70" size it is best to check the very early models. This seal kit has 1 ring seal and 1 cup seal, the later kit has 2 ring seals ([linl]GRK1006[/link]).