The front wheel bearings for the Cooper "S" were all originally these 'roller' bearing style. The design of the roller rather than the more common ball bearing is such that they will last much longer under higher side loading. Thus as we have developed wider rims and stickier tires it is becoming increasing critical to use roller in both the front and rear of all Minis. These bearings are not only stock in the "S" but are also a direct replacement for the ball bearing type as found on most other Minis. Two kits needed to replace both sides of vehicle. The roller bearing for the rear of all Minis can be ordered as part# GHB147K.