feels like mine clamps the plastic rails and the metal of the bed; came with bulkhead seal which is about an inch, seems to seal well...no water after rains while parked or on highway since I Got it...also picked up tailgate gap seal and I think that helps as well
I have one on my Ranger, no brackets included, but 2 extra mounts with straps for the front of the cover...got it like 3 weeks ago, from, gator, so should be the newest version