The mat works well under a desk chair with casters sitting on a carpeted floor. It protects the carpet without leaving irremovable imprints in the floor. Best of all the mat was on sale and I got a very good buy.
I purchased two of these chairmats for a home office. They work so well and it's nice to know that the new carpet won't be damaged by rolling office chairs. Only con was the strong plastic smell when I first purchased them.
This is good for low pile carpet. Do not use for higher thickness carpet. The Mat will crack in time if you do. Otherwise it is a great protection for your carpet.