Width of bracket interior ~114mm Height of bracket interior ~60mm
"Bracket with notch" has a small notch on 2 sides that key into a groove on the corner of the power supply. "Bracket no notch" does not have this slot, so it can be adjusted to fit. One bracket with the notch could be enough to mount to single 20x20mm extrusion.
Prints well in PLA, ABS. 2-3 shells ~1mm wall thickness 20%+ fill rate