This is the second matt that I have purchased. I use it on a plush carpet and over time it breaks up. It does seem to discolor over time. I can't remember how long I have had the one I have now. It does make it possible to roll my chair on the carpet and saves the carpet from the chair.
Many sizes are available but this one covers the entire area. Our desk chair with rollers moves freely now to all areas used at our 60 X 30 desk with return. Brand new hardwood floors and no worry now!
I liked the old mats that had graduated edges as opposed to what is available now. It is sometime difficult to go from the carpet to the mat and the wheeled chair get stuck.
Someone had rolled these pads up and taped them using clear packing tape. It was a good idea to carry them easily but it took about 30 minutes with a rag and goo-gone to remove all of the tape residue.
I am using this product on top of a low pile carpet and it works well. It is colorless so it is not distracting. It stays securely on the carpet and can be easily wiped. The only "con" was that the tape around the rolled up mat needed to be cleaned off with an all purpose household product (took some elbow grease) but Staples Customer Service said that they are working on this with the manufacturer.