5 stars for 3 of the mats, 4 stars for 1. I bought 4 of these and one of them curls under where it hits the wall under the desk. I also have to move it back into its space daily. Most likely because it is a hard floor mat and slides easily.  Not sure why the one is a problem and the others are not though. However, they are made from a good material. Have had these for about 1 year and have not had any cracking despite the number of people who use the desk chair the mat is under who vary in weight from 120 to over 400 lbs.