Don't be distracted by the cheapest price. Know the depth of your carpet; if you get this one and your carpet is too thick you'll just end up sinking and defeating the purpose of the mat. Be sure to get the correct one for your carpet.
I purchased the version that was advertised as suitable for plush carpet. When in use the mat has developed dimples where the casters rest which makes it difficult to roll the chair easily. It should probably been thicker.
The mat does just what is expected on our carpet. I love the larger size as it allows the wheels on the chair to move freely as I get in and out of it.