Theses parts are made to hold the lead screws on the P3Steel in place. The bearing can go over or under the metalic part depending of the clearance you have with your printer.
The design has been inspired by this thing (https://www.thingiverse.com/thing:1841693). But has been entirely re-designed because theses files did not match my frame. The holes in the parts were about 5mm away from the actual holes.
*Please check the dimentions of the arm on your printer !* A PDF is available on the files with all the dimentions.