*Stock Is Limited!* New Top Quality BSA Unit Twins Crankshaft Roller Bearing Shim Cup Retainer. With the Modern Replacement Roller Bearings on the Market today, they are “Slightly” different from the Original Hoffmann Roller Bearings, which means you have to use this Shim Cup in Conjunction! Specifically, New RHP Roller Bearings (70-2879 or 68-0625) have a slightly Wider Inner Race then the Stock Hoffmann Bearings causing the Shim Cup not to fully fit over the Race! If your currently experiencing that problem, then this is what you need! If your using the Original Hoffmann Roller Bearing, this will also work for your application! Fits all BSA A50 & A65 Unit Twins (Royal Star, Lightning, Thunderbolt, Firebird, Spitfire, Etc) from 1966-1972. Please refer to your parts catalog for proper fitment.*****Please note that this Shim Cup is only for “Roller Bearings” as used from 1966-1972 and not for the Early “Ball Bearings”!*****Made in New ZealandO.E.M Part number is 68-0638 or 71-3288