Bought two of these one for me and the other for my spouse. Mine replaced a 11 year old carpet mat and the wife's was 4 years old. These are too thin. If you sit in your chair for 30 minutes the rollers sinks into the mat due to the thin thickness. My previous mat was significantly thicker. Did not realize it until I got these home. It's slightly smaller in both dimensions but it still works for my "L" shape computer desk and my wifes regular shape desk. I suggest you look for something thicker. Looking at my mat I see that several of the dimples have not recovered from yesterday. My old one went 9 years before it cracked don't expect this one to last any where near that long.
This mat slides all over with the chair. Do not like it at all. Should have bought the more expensive one with the little tabs that dig into the rug to hold it.