Pop rivets hold the snaps in place, a little note on why the snaps are so far from the top of the body. I took it to a friends upholstery shop originally to have it done , well he didn`t custom make it he bought it from a catalog and put it on and put the snaps were they are now " TOO LOW". I took it to another shop a few months later and he custom made the one on there now. The one on my Hemi Q.C. has the rails that attach to the top of the bed, I bought it from Summit, I think its an Extang and haven`t had any problems except when its cold its hard to pull the cover to snap all the snaps.