The Creality CR10S-Pro features a run-out sensor but the entry point and position of the filament reel mean that incoming filament can scrape against the edge of the run-out entry creating fragments and waste that can be drawn into the extruder.
These two parts allow the filament to be guided smoothly down and into the run-out entry point without snagging either on that hole or the frame top.
The curved part slides onto the run-out sensor as shown in the photo. The flat part is attached to the top of the z-axis frame on the left. Remove the two screws holding the lead screw guide, put the part in place and screw back up tightly.
They'll probably work fine with any material - my first version was with PLA and it seemed to have no undue stress - but PETG or ABS might last longer.
v4 - slight adjustments to fitting