The mat will prevent dirt from shoes from getting on your floor. The legs of the chair will indent the mat. However it is a small problem. This mat is sufficient for my computer room.
The mat wasn't rolled when delivered and had some lumps but it flattened right away. It helps my chair glide while protecting the carpet underneath as I had hoped and looks good.
My fault I have a professional office chair and standard house carpet. Rollers on chair sunk into mat within a day without anyone sitting in chair. Had to return it. Store took it back with no problem.
I know 200 lbs is heavy but I expected this mat to not sink into the carpet. I am not completely happy with it. Time will really tell my satisfaction level.