FAG bearings are technical FAG spindle bearings: spindle bearings are single-row angular contact ball bearings consisting of solid inner ring, outer ring, ball, and cage assemblies with solid window retainers. They can't be dismantled. These bearings may be open or sealed. The tolerances of the spindle bearings are limited. They are particularly suitable for bearing layouts that require very high directional accuracy and speed. They are particularly suited to the bearing arrangement of the machine tool shaft.