I don't think you can find a better priced carpet mat anywhere. The quality is comparable to the price. On thick carpet the mat sinks and chair traces are easily visible.
The two chair mats we bought work very well at our two work stations: my home office and my wife's sewing machine cabinet. They enable us to move our older office chairs between desks and work tables - over wall-to-wall carpet.
The plastic is not very thick so there are indents from the chairs wheels. otherwise it makes it easier to roll around. also protects carpet it was nice to have a choice of sizes. Store manager wrapper it in a roll so it was easy to carry.