This mattress cover is wonderful.  When I first unpacked it I was more than worried because I expected the bottom to have elastic all the way around it to keep it on the mattress. I was wrong.  It hugs the mattress and doesn't move.  It is thick and comfortable but very cool. Since I sleep very warm I bought this to cover a new cool gel memory foam mattress. The mattress is cool, the mattress cover is cool and I am having the best sleep ever.  Highly recommend this mattress cover.