After measuring the screw head slots on the back, one on the center line and one on the outside edge, I drilled the screw holes and then attempted to mount the hook.  Did not fit on the screw heads, could not get it on all three.  Pulled it down and then measured the screw head slots and found on edge was 300mm from the center, and the other is 304mm.  I was forced to lower the wall hook and drill new holes again to account for the asymmetry.  Disappointed that Umbra's poor quality control forced the extra work.