The author remixed this model.
KevinAkaSam's Belted-Z mod for the Ender 3 includes a modification for adding Z-braces.
The original Z-brace mod requires an M5 tap to add threads to the top profile for the Ender 3.
This mod modifies the top brackets and adds threads on both sides of the profile so that it does not need a tap. The Z-brace is very sturdy.
Requires:
Print the two files in this model instead of (from KevinAkaSam's Github):
The bottom brackets are from the original Bottom_Right.stl (from Thingiverse model for Z-Braces)
Use your slicer to mirror for the other side.