Núm vặn Extruder Micro Swiss

The numbers at the end of the file names indicate the diameter of the hole in the extruder knob STL. 

The stepper motor shaft is precisely 5.00mm but the diameter of the hole in a 3D printed object will vary depending on how the slicer software and 3D printer are calibrated, so there are multiple STL files available with hole sizes ranging from 5.10mm to 5.32mm in diameter.

First print the knob featuring the 5.20mm diameter hole Knob5.20mm_Default.stl, test how it fits, and then print a different size if it's either too loose or too tight to fit onto the stepper motor shaft.