GRW bearings are the best you can get.  Period.  If you want top quality, then these are the bearings you want.  Used by top motor builders around the world for Eurosport and G7 motors, these bearings are perfect for endbells or for the newer generation of F1 Eurosport cans, and are designed to handle the higher load generated by high-end motors.  These bearings measure 2 X 5 X 1.5mm and are open, non-flanged.