STL file should be to scale, (unless thingiverse shrinks them for compression). This is a cable management system, spec'd from a Geeetech A10(/M/D), and should fit similar models.
This bracket curves wrap around tower piece's side fillets for better grip, and the cylindrical prongs are designed to be a tight fit inside the holes, (as seen in the second picture).
Forgive my print quality: this was my second print ever on my own printer
Solidworks and a Dial Caliper