How are you hanging the slabs without a frame?
Probably a big NO-NO, but I'm using LARGE Command Strips. Carefully applying them without bending the slab case. !!!!!BUT!!!!!, it wouldn't be something I'd do with a comic worth more than a couple of hundred! It says right on the back of the box "Do not use to hang valuables or collectables"! The most valuable I have on the wall is the CGC 9.9 Walking Dead #1 New York Variant. That being said, I don't want any of my books to hit the floor, so I check them frequently!