Began cracking at 6 months continued to worsen until it was unusable at 9 months. Shortest-lived mat I've ever had by far. Will not buy one of these from Staples again. With their return policy I'm stuck with the loss.
I have medium pile carpet and my casters sink into it and create divots/depressions and doesn't roll. I will return it and hope the one for heavy duty carpet works. The chair and I probably weigh 230 lbs.
Shifts position with movement of chair and as a result it tends to develop humps/bulges due to stresses on the plastic. Also the mat develops indentations or pockets where the chair weight presses downward under the casters.