The mattress that came with our futon was thin enough that we could feel the metal bars under the mattress while sitting or lying down.  We placed this Zoomie Kids mattress on our futon and the mattress is thick enough that I cannot feel the bars at all.  Of course I haven't had the mattress for very long so I don't know how much it will compress over the years.  It's very confortable, provides good support and not lumpy.  Seems like a very good mattress for the price I paid.