The Staples carpet chair mat crystal clear 45x53 is the chair mat I buy for all our employees. The mat lasts a few years before it starts to chip in places from wear and tear. It's inexpensive so it isn't a big deal to replace every few years.
We got a chair mat for our computer desk over 10 years ago. It took over 8 years for it to form a spot that the wheels rolled into. The one I just got was the best one they had. It took less then 2 weeks for it to form a spot for the wheels to roll into. If I knew that I would of just used the old one.
product is a little thin and a heavy chair wheel leaves an indentation. also it was supposed to work well on heavy pile carpet but it works better on light pile carpet.