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.
This said it would be at my home the next day - with free shipping - and it was! That's pretty surprising considering that I live in the extreme boonies... This is perfect to protect the hardwood floors in my home office. It's a nice size too.
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.
This does not have to sharp pointy pins on the bottom. As a result it slides on the carpet and every few days i have to pull it back where it belongs. Wish at least some of the pins on the bottom were the sharp ones. They stay put.