You don't need the box...all the beds have the slats on which you put the mattress. Our mattress was too tall, so we ended up putting it on the floor. For two of the bedrooms we got the beds and mattress from BO Concept. They had a memory foam. Apparently it is very comfortable (that is what all my guests said)

I have sold mattresses without box springs for years the box spring has no affect on your comfort if you look at them all there is is a box of springs with wood slats on top and they can charge you outrageous money for this I have never owned a box spring and most people in Europe don't own them either get the mattress that feels good on the box spring and it will feel good on your platform. have memory foam mattress on both my guest bed and mine and our guests always make comments about how comfy they were.