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.
I bought this particular one because the dimensions best fit our desk but this particular model is not as heavy duty as others we’d seen. It’s a little too flexible for what I like plus the portion to roll the chair on is not as large as I’d like. The other mats we’d ween were better other than the portion that fits into the desk opening was 25” and I only had a 24” opening so that didn’t work for me. My old mat was perfect size but that size was not available through Staples.