OK this clearly states that it is only good for carpet with 1/4 inch pile. Admittedly my carpet is deeper than that. But this was the only choice in the right size for my office. Plus the thicker mats are way too expensive in addition to being too large. If you have decent carpet don't bother. C'mon Staples can't you stock something that is the right size with decent construction?
On medium pile carpet the chair creates divots that are so deep it's hard to roll out of them. They aren't permanent divots - but at the time you are trying to roll out they still inhibit your motion. The mat also creeps forward but I haven't had one before so maybe they all do?