When used with a plush carpet w/one inch pad it will creep as chair rolls on it. Needs to be more heavy duty with longer pins to hold it in place on the carpet.
My office chair left dents in the mat without anyone even sitting in the chair! This is definitely not worth the money. The dents don't pop back out they are there for good. When I sat it it was hard to move because the chair rollers were in the dents.
We have glued down very thin carpeting in our office and the glue had given away causing ripples in the carpet. I thought the .85 mil might be too flimsy but was pleasantly surprised. These mats are surprising adequate for our use. We've just had them a couple of weeks so only time will tell if they will discolor with age.