this chair mat smells awfull even after one night with an open window you can smell the chemicals coming out of that thing. Most likely it´s made out of PVC containing phthalate plasticizers which are unhealthy. I will return it...
A chair with rollers in any one spot for more that a few minutes on this chairmat develops a sinking spot. It is not thick enough for a chair with rollers on carpet. I weigh 160 and my chair is around 25lbs. That should not happen.