Surprised at the extend the chair rollers "sink" into the mat if you are seated in the same spot any length of time. However once you do move the 'depressed" area of the mat does return to a "normal" position. I just hope we don't see cracks start to appear after having them for a while
This was supposed to be for plush carpet over 3/4 in think. While it is a high quality mat my chair rollers sink in leaving deep dents that are hard to roll out of. The bottom is made of small bars rather than sharp spikes with is nice but they are only about 1/4 in. in length (depth) so really just sit on top of the carpet and offer no real support to the mat.