It looks like the same system with the arms but a bit bulkier. I got rid of my x5 awhile ago but rememver it being a bit thicker then the x50 so I wouldn't get the akron without planning on modifying it. The akron would probally fit a slim Palm type unit the best but I find it adequate for my x50v just want to shave the foam a but so that I can snug it up a bit more.
I will try to decribe the system for you there are two arms on the side with foam that sqeeze together to hold the unit in place. The foam is cut in a "v" so that in a ideal setup the unit would sit in the valley. With my x50v it sits on outer edge of the "v" not the valley so there is less foam left before it
could slip out.