How much float do the Speedplay Zero pedals have? I was reading up that the "Speedplay zero" has a unique float and a wide range, but when reading up on the page dedicated to the "Speedplay zero" it mentions thatit is for  Rider who prefers a fixed (no float) or limited-float pedal system in the section labeled "why get this pedal."  It had also mentioned on the top of the page that it has a varying float, and that it has multiple adjustments to adjust the cleats perfectly for yourself.

I am curious if anyone has any experience with these as I am looking for a pedal that has a good amount of float so that I do not experience knee injury.  I heard the Speedplays and "Keywin" companies were good for that.
I read the following, from their website as having the option to either lock them in place and use them as a fixed cleat, or use them with up to 15º of adjustable float, which considering many are only about 7º seems like a lot. 


  By thinking "outside the box", we created and patented the most
  technically advanced pedal system ever, featuring your choice of
  either a fixed position or up to 15 degrees of micro-adjustable float


I personally have no experience with them though, Nor have i heard much about them, that is just how i interpreted it.