Mobile detection

How does nopcommerce know to choose all mobile pages?
I know it uses the fiftyone.foundation.dll in the global.asax page.

There is no web.config reference? There is no route that I can see and there is no code that I can see referencing whether a mobile view should be detected.

So how does nopcommerce know to use xxx.mobile views?

I've noticed that he fiftyone declaration has been removed fom v2.6. I was looking at 2.5.

The question still stands how is the mobile detection done.