After the first time I sat in the chair in front of my computer the chair left notches in the surface of the chair mat. I guess I should have gotten a mat with a harder surface.
If you are looking for a mat that will have a stable surface over a deep pile carpet I highly suggest that you look somewhere else because after much time studying the catalog Staples offers this was the best I could identify and it is inadequate. Problem is that the plastic is soft and very pliable. The wheels of the desk chair sink in and form a deep pocket very quickly Then attempting to roll the desk chair to another position it's stuck in the pockets so moving takes more effort that anticipated. Many Years ago I purchased another high-end mat for my wife's desk I might have purchased it from Staples. It is over the same carpet: no issues; stable; no cracks; and flat.