This is a Classic Mini ball joint

The Mini is the classic front engine, front drive car that really abuses the front suspension and the entire load is transmitted through the top and bottom ball joints. They do wear and should be inspected when you're working on the CVs or wheel bearings; when you detect slop, replace them. This kit includes one upper and one lower ball joint, locktabs, shims, nuts and washers. Everything except grease nipples. Only 2 each of the shims are included in the set, extras are available as 2A4239 003" and 2A4240  005" plus 2A4241  010"which is usually sufficient.