We have had memory foam mattresses in both our houses and RV's since 2005.  The one I just replaced was 11 years old.  It was starting to have soft spots. This arrived 2 days early.  We opened it and placed on our solid wooden platform frame.  With in the first 24 hours it had expanded to about 9.5" …. After 48 hours it was at the full 10"s.Have been sleeping COMFORTABLY on this for a week now... and I never would have  believed the difference in my back pain.  With the old one I would get up in the morning and immediately do my lower back stretches to get moving.  I still do my stretches... but I get out of bed with very little pain.The price on this this is VERY REASONABLE!!Oh..and as the previous posters and even a card enclosed with the mattress state... there is a rubbery odor...but it was totally gone with in the 3 days.We are very happy!