Would not buy again and thinking about returning the mats. They are not thick enough and I am using them on very short pile commercial carpet. The chair is leaving permanent dents in the plastic when I sit on it and I am not overweight whatsoever. My old mats that were replaced by these were in better shape after 10 years than this new set only being 10 days old.
Currently have mat on top of carpet. Chair's rollers tend to sink into the mat quickly so rolling can be difficult. It does protect the carpet (which was the goal). That said I'll probably invest in something a little better/thicker next time around.