MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
The M4 x 20 worked well for my printer. I'm thinking of mounting this part on the top holes as it kind of crowds the fan.
Also, my advice to anyone reading this is to attach the fan last as it's very difficult to attach the adapter when the fan is on.