Universal Rocks 24-Inch by 12-Inch Rocky Aquarium/Reptile Rigid Foam Background

This background looks like real rock I got it actually for a small 5 gallon aquarium but haven't installed it yet it is probably only about 3/4 inch thick, which is one of the things I was concerned about it is made of very thick foam so it will need to be cut and wedged into the tank to hold into place other reviewers are right, I don't know how the two clips that come with it are supposed to hold it in place