I am using the chair mat on low pile carpet and the chair wheels tend to make indentations in the flexible plastic. My other chair mat that finally wore out didn’t do that.
This mat is nominated for 3/8" carpet pile. I use it in a workplace organized in a bedroom with the usual soft wall to wall carpet. I measured the pile using a paper clip -- the technique suggested everywhere where the mats are sold. It was difficult to tell exactly because carpet hairs are uneven and bend easily. I eventually decided that they are 3/8" or less so I ordered this mat. Apparently my measurements were off. I got the mat with the cleats shorter than necessary so it tends to drift slowly over the carpet to one side with the rate of about an inch per day. When you buy the mat to use on a home-style carpet (as opposed to a firm office style) choose cleats longer than it would be required per measurement. Otherwise the mat is good and works very well.
Arrived when scheduled by free delivery. Definitely go for this sturdier mat if your carpet has any sort of pile. It will still dimple with concentrated pressure over a small area for example the leg of a non-rolling chair but works well for rolling office chairs.
I have had a terrible time finding a chair mat that doesn't slide on our carpet. (Would you believe 6 attempts) This one is designed for a "1" pile carpet" and is thicker that previous mats I've tried. However it still moves until it hits my desk but at least so far it has not curled up. So I plan to keep it for awhile.