In order to fit your phone in it, you need to pull the two arms apart, but this requires so much force that I worry it will damage the phone. It takes force, even for a very strong person, and it is impossible to put your phone in it or take it out without using two hands.
As it attaches to the windscreen, this is really awkward as I could not comfortably reach the windscreen with both arms while I am in my drivers seat. I also imagine, given the force required, that the suction cup it attaches with will not last long. The optional sticky tape mount is actually just a surface for the suction cup to attach to so without the suction cup, there's no way to attach it.
I can't use this. I will need to buy something else.