DMI Folding Bed Board A too-soft mattress can be bad for your back because it does not provide the proper support. Just slide this board between your mattress and box spring and enjoy more firmness and a better night's rest. It's also useful in shoring up a sagging mattress. The board is foldable, making it easy to carry and store. Features Helps add firmness to too-soft or sagging mattresses to better support your back Slide the bed board between the mattress and box spring. Conveniently folds into four equal sections, making it easy to carry and store Overall size: 30 x 60 in.