The chair mat works well under my large desk. I have it sitting on wall to wall berber carpet. It's not super thick plastic so it has divots where my office chair wheels generally sit. This makes it a bit annoying to push away from the desk though I'm hoping over time it will even out.
The material is not thick enough to prevent the roller feet of my chair from digging in making little craters that become hard to roll across. Flimsy and doesn’t really do the job. I would not recommend it if you can get something better.
It's so different now not being able to be in person to purchase certain things. This looked normal on line...actually constantly moves/will not stay in place and doesn't support the chair properly. Hoping it may be okay enough to get the job done.