We've tried a couple of different memory foams, but find that the foam used by Raskelf (The Duvalay makers) is very, very good. We've found the cheaper foam is not as comfy and gets too hot in summer. As for the Duvalay, we bought one for our daughter, but she didn't get on with it. So If anyone would like an over-rated, expensive, complicated, sleeping bag, then we have one for sale