The mattress protector was not easy to put on, was extremely tight fit for a total of 13 inches, but claims to go up to 18 inches. It was a challenge to get the zippered top attached and zipped all the way around the bed. But if you follow the measley directions perfectly, have some help, an go slow it will work out. The end result so far seems very good I now have a high quality waterproof mattress protector that holds my memory foam topper and mattress pad topper in place on my bed, something I wanted since they were purchased but never achieved til now. So although not a totally perfect product, it has some terrific plus points I can live with.