I like this size shape and quality of this mat. My only negative is that despite it having little plastic spikes on its underside it shifts position to easily and I keep having to adjust it.
The wheels of my char sre sinking into the mat and it is hard to move it out of the sunk area. My carpet thickness using the paper clip method is 1/4". I am very unhappy with this purchase.
The plastic is a little too soft as my roller chair sinks into the divots made by the legs and it is hard to roll out of them. I expected it to be harder plastic to prevent that.