I recently bought what is called a hybrid mattress as my old one was shot. It is made of both memory foam AND steel coils. When it arrived, the minute I took the plastic wrapper off, it started hissing as air rushed in to inflate it. It was quite amazing to watch! But then I got worried, thinking I had bought just an air mattress, not a true mattress. I called the manufacturer and found ouot that NO it was not an air mattress although air IS used to put it into its final shape. I have to say - this is the most comfortable mattress I have ever owned. I am sleeping through the night every night. The one I got is an Oliver Smith mattress, and I found it on Ebay or maybe Amazon. I LOVE this mattress.