The "Staples® Flat Pile Carpet Chair Mat 36" x 48" Lip" isn't a great fit for the L-shaped desk I have. It fits just right up against the sides of the desk so I can't go a size larger; however the lip isn't wide enough and the front right wheel tends to fall off. I also find that if I roll too far away from the center of the desk the back wheel falls off the mat. If I had the keyboard installed in the corner of the L-shaped desk this would not work at all. However it works sufficiently since the keyboard is located facing forward.
Matt is too thin period. Chair wheels dig deep into the matt/carpet. Much different than the smooth glide of my previous matt (worn out after 10-yrs). I guess it provides carpet protection but it's definitely not a "smooth glide". I don't recommend buying.