Angular contact ball bearings have higher limited rotational speed ,it can take radial and axial loads at the same time,single-roe angular contact ball bearings can only take single axial loads,so it is always set in pairs ,when setting in pairs ,it would be most convenient to choose the paired angular contact ball bearing which was adjusted beforehand. The cage meterial can be brass,synthetic resin and so on.It depends on the bearing typy and using condition.