I purchased the 5 inch Sleep Master mattress because my mattress was not comfortable and I have back problems. I am amazed at how comfortable this one is. I bought the full size as I already have a full size and just placed on top of the other one I have. It is slightly bigger than my full size mattress but much more comfortable to sleep on. Seems well made and as if it’s going to be long lasting. It is firm and does not sink and it is not full of springs either. Helped add height to my bed making it easier to get up off. My back has not been aching when I try to get up from bed since getting this mattress.