This one replaced a Perfect Sleeper that was 9 1/2 years old, I felt some sag in it but it still slept well. I could not believe how much firmer and more comfortable this new perfect sleeper was, I am actually sleeping more sound and through the night more. My back is thankful and I would truly recommend this mattress, still can not believe how much difference of comfort there is within 9 1/2 years between mattresses. The only downside is that my old mattress had a little bit more stiffness at the edges when getting out of it, but nothing compared to the overall comfort.