The size and grips on the bottom are working great. It is already indented where the wheels of the chair are. Not sure if that is normal for chair mats.
It is made for very thin carpet. While rolling over with an office chair the mat moves; after it has moves three inches I have to reposition it. The reason it moves: the protruding fingers on the back-side are way too short and not pointed enough to grip into normal carpeting.