I have the King sized Casper mattress and I find the mattress cover is too big. It does have super grip underneath, but the top pad part of the mattress cover extends over the top and down the side of the mattress a couple inches which I find odd. Because of this, when I sleep, the mattress cover creates folds and wrinkles underneath where I lay which is annoying. I will say the cover is nice and soft, thick, and well made, I'm just very disappointed with the fit of the cover on the mattress.