It has been in place only a few days but I find mat dimples just with the unburdened weight of a wood desk chair. Mat is workable but I believe mat of soft material. Mat sits on very low pile Berber rug.
I purchased this to go on top of the carpet in my office and it does work but it is thin. I would go for the next one up if I were to purchase one again.
I bought this product because of the majority of the reviews were great. A few did remark of how the mat gets indentations from the chair rolling on it. Which I am gaving problems with. Also the mat constantly moves. I am not happy with my purchase. Wish I could return it!