GRW SS682 2Z 2MM X 5MM Ultra High Precision Motor Ball Bearing - SHIELDED & UNFLANGED . This bearing is recommended for Cobalt motor application up through and including Group 7 Open Qualifying Motors. In short – the very most demanding applications that slot car motors can dish out. Why GRW? For those who have experienced the GRW performance we’re singing to the choir. For the uninitiated, we can start by saying that the radial play is about a third of many other bearings on the market. Additionally GRW subtly altered the alloying of the 400 series stainless steel to improve the performance of their bearings in a remarkable manner. Not only does it provide the corrosion resistance afforded by stainless steel but the surface finish is improved to provide greater freedom of rotation and better wear resistance for prolonged durability.