The mattress is longer then a twin, and thinner then the expected 6 inches. It also "walks" even though it says it doesn't. I think the reason it walks is because it's so very light. I didn't expect it to be as light as it is. But it sure does make it easier to move. Also, it could use some handles for moving. These are the only reasons I rated it 4 stars. As for the quality, pretty darn good! My fitbit sleep scores actually jumped sleeping on this!