I bought this because it was meant for medium one carpet which is exactly what I have. While it is better than some mattress I have found that it is still thin and as a result the chair creates 'dents' after just an hour of sitting that prevent the chair rolling. I'm only 160 lbs so I didn't expect that to be a problem. It does seem to recover so the divots aren't permanent but can be frustrating if you need to move your chair frequently. But it IS better than anything sold for low pile carpets - just don't expect perfection
I like the chair mat fine but would have liked a plain rectangle shape but could not find one on the web site. I had to cut off the piece that juts under the desk because it had the rubber studs inderneath the mat and the floor under the desk is hardwood. Otherwise great value sturdy mat for our area rug.