How does the double threading on the MetMo Pen work?

The double threading uses 6 clockwise multi-start threads, which means that you machine a thread starting from 0 degrees then index the machine by 45 degrees and machine the exact same thread again, then again, then again, then again, then again. 

And then repeat all of that machining anti-clockwise.

One clockwise nut is machined with the same multi-start thread pattern and one anti-clockwise version, which allows the nuts to smoothly thread on to the Pen. And then the magic happens.