Just to clarify: The Helico Matic hub does not use a "freehub." Instead it has helical splines to carry the Helico Matic specific freewheel (as opposed to threads for traditional freewheels and visible in the photo below).
And I'm shocked to see in The Golden Boy's post quoting the late Sheldon Brown who referred to a Helico Matic as a "cassette."
It truly is a freewheel.
