The mat is not firm enough and the wheels of the chair create indentations in the mat which make it difficult to roll the chair while sitting in it. I would not buy this mat again for use on carpet.
For a heavy fellow like me (230lbs) it has developed small ruts where the chair wheels usually rest. It requires effort to move out of the rut and effort to keep it from sliding in. Shifting the mat placement has helped but now new ruts are developing. Should have bought a thicker one.
This was replacing another Staples chair mat that had lasted for a number of years. However this one was much different when we got it home. It felt strong enough but does not work on the same carpet as the old one without the holes already appearing where the wheels sit. The chair sinks into those "holes" and is hard to move around. Would not recommend this one--get the much more expensive one if you want it to work and last.