When I downloaded this mod, I checked the X tensioner and you will need the original Prusa pulley 623, but If you wanna use Caribou pulley 2gt 16T Toothless, you can check this pulley is “dancing” inside tensioner.

I prefer little pulley because with this pulley the X belt is aligned.

The Prusa pulley (623) width is 9mm and inside tensioner dimension is 9,5mm.

The Caribou pulley (2gt16T) width is 8.5mm and inside dimension tensioner I modified to 9mm.

Now you can use this little and nice pulley with this excellent X tensioner.

The 2 printer photos are linear rail mods, not compatible with this tensioner, I am only showing these photos to make the X-belt alignment visible.