Unless your carpet is very thin (or old) this mat is too flimsy to work. The wheels of the desk chair make deep indentations and it becomes impossible to roll across the mat. Unfortunately it will need to be returned.
The mat is completely unsatisfactory. It came tightly rolled in a box. It was very difficult getting unrolled to be able to lay on the floor and even now the edges are still raised and are a tripping hazard. Otherwise it does the job rolling the chair on the carpeting.
We got this for a low/med carpet thickness with an office chair that has wheels. Within a few minutes of sitting in the chair there were visible indentations from the wheels. It's better than not having anything on the carpet. I also purchased a more expensive Floortex one and it is MUCH better quality than the Staples one. This one is just good enough as long as you regularly move the chair so the indentations to stay in the same place.
Chair sinks into mat after awhile so you have to try to roll past the divot created. (I am not that heavy). The mat does scoot around on the carpet though most every mat I have had does so. Otherwise the mat works okay.