BUDGET FOAM, We waste very little foam here at foam4u. All our off cuts are either shredded as cushion filler, or are bonded together and cut to size. As part of a national mattresses recycling program we harvest some budget from from hospital mattresses LIGHT-WEIGHT FOAM, This foam is only suitable as a pop top mattress for small children, FIRM BLUE, This foam is both firm and high density and is a great choice for a pop top roof mattress RG50 FIRM, This is without a doubt the best option for a Pop-Top roof mattress The density of this product helps to provide extra support. MEMORY FOAM, Only to be used as a topper not really suitable as a stand alone mattress as you will sink through the foam. FOAM & MEMORY COMBO, Best of both worlds