This thing is incredible! Everyone who's sat and laid on my bed has just fallen in live with it because of this! I have a Queen sized mattress with a pillow top PLUS all four inches of this! Its like sleeping on a heavenly little cloud! Oh! Ive never had such a good nights sleep. As soon as you lay down it just molds to you, its amazing! WARNING! I prefer a softer mattress, so if you prefer a more firmer, stiff mattress this may not be for you. You can always go try them out at furniture stores and places like JCPenny and whatnot. It does add somewhat of a problem with the sheets and the extra length it adds to the sides of the mattress. So some of those little under the bed, corner strappy things would be a good investment.