The ball screw bearings are divided into two types as following: l .The BK,EK,FK fixed-side support unit contains two angular contact bearings that provide both axial and rotational support for the ball screw. 2. The BF,EF,FF supported-side support unit has only a standard ball bearing that provides rotational support on the end of the ball screw opposite of where the drive occurs (typically a motor or pulley). 3. Our standard ball screws are supplied with machining that will work with these supports without modification.