Ball Screw Support Unit housing FK screw holder engraving machine accessories
https://www.hyballscrew.com/product/ball-screw-support-base/
FK/FF end supports are sometimes referred to as "flange" styles. There are mounting holes in the flange and the holes in the machine frame receive the round bearing bodies. Bolt the flange to hold in place.
FK "Fixed" end supports consist of two angular contact bearings that provide axial and rotational support for the ball screw.