I honestly have no idea what our mattress is . We got it from my parents. They had it for a couple of years, but only my mom slept on it. It's super-firm, which dh likes, and I did for a time. But when I lost weight, I noticed that my hip/back on the side I sleep on would hurt terribly when I woke up in the morning. I posted something about it on FB, and one of my running friends gave me her memory foam mattress pad on Sunday. I was expecting one of those egg-carton type pad, but this sucker is about 3-4" thick, and INCREDIBLE!! So now we have the firm base layer, and the memory foam layer I can finally get comfortable on. I've slept better the last three nights than I have in over a year.