Bought two of these two weeks ago. Put them on typical carpet and I bought the one that was recommended for this carpet (medium 3/8" to 3/4" pile). And they just don't stay still. I have to get up move my chair off them and move it back 2 or 3 times every day. Very annoying. Also when you sit in the same spot for a while they develop indents around the wheels and its actually a fair amount of effort to get get the chair out of them so that I can rotate around and get out of the chair. Not a happy customer here.
Might be too early say this is a waste of money but there are already depressions in the chair mat that don't recover after a day of use. I have a medium-pile carpet with pad and if this mat doesn't hold up better I will switch to a harder mat maybe wood.