Angular Contact Ball Bearings sealed Angular Contact Ball Bearings ensure that the bearings are in the best possible condition, free of contamination, before and during operation to provide high level machining performance.Sealed single row angular contact ball bearings can be used in a variety of grease lubricated applications where today single row angular contact ball bearings and exter - nal seals are used. In cases where angular contact ball bearings are lubricated with oil, sealed variants can provide a cost-effective.