These clips replace the standard mounting blocks on the back of the controller / LCD. The clips will hold the PCBA and allow the controller to clip on to a DIN rail. I used this to attach a Raspberry Pi 4 with 7" touchscreen to the front of my printer.
Other related items here:
DIN Rail mount for OctoPrint / Prusa MK3S LCD controller:
https://www.printables.com/model/234436-octoprint-din-rail-mount-prusa-mk3s-lcd-controller
DIN rail end caps:
https://www.printables.com/model/234447-din-rail-caps-for-prusa-mk3s-controller-rail
Raspberry Pi / 7" touchscreen housing DIN mount clips:
https://www.printables.com/model/234463-din-rail-mounting-clips-for-7-raspberry-pi-enclosu
DIN rail spacer block (styled to match MK3S / LCD controller):
https://www.printables.com/model/234444-octopi-controller-din-rail-spacer-block-styled-to-
The author remixed this model.