Protects the carpet; chair rollers dent surface so you need to push the chair out of one position to make it to another. However main objective is to protect the carpet and it does an okay job in that respect.
Recently had our hardwood floors re-finished with a quality finish. The floor mat in the area of our desk reveals the finish without taking away from the rest of the quality floor.
It's too flexible. I weigh 215lbs and when I'm in my chair on this mat the sides come up off the carpet and stay that way sometimes becoming a trip hazard. The chair's wheels also sink into the mat somewhat making it hard to move.