The mat shifts as a result of moving the chair around. I have only had it a short time and it already has areas that are wore which cause the wheels of the chair to stick in the worn areas/grooves.
I find the office pad I bought is a little thin using it on a carpet. It would be fine if I was using over a hard surface floor. I think the for mats should be shown that it be used over a carpet or a hard floor. The difference being the one I bought is to thin to use over a carpet since it sinks into the carpet and stiffer one would not sink into the carpet.
Originally ordered this Chair Mat to replace one that was falling apart. It had also been purchased at Staples about 10ears ago. I expect that this one will last just as long.
While the mat doesn't quite work with my L-shape desk (the smaller part doesn't quite fit far enough under the desk to protect the carpet where my feet sit) it is a sturdy mat that looks like it will hold up to extended use. It has also stayed in place on my medium pile carpet and not moved as I have rolled around. I have a fairly large and heavy chair and the mat is not developing any grooves or dips. I hope it will hold up to my first impressions!