Went to purchase chair mat in store. This was only model they had. Too thin. After only a few hours rollers on chair created permanent divots in mat. total waste of time and money.
I'm using on a medium pile carpet. Yes it dents and shifts a bit but they all do on medium carpet. I don't mind moving the mat back every few days. The material is a softer vinyl than my old one so I expect it won't break as readily. Dents are OK breaks are not. I wanted something inexpensive for a year or so until I move and this one will do OK.