Product details:
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. Also useful in shoring up a sagging mattress. Conveniently folds into four 15" sections, making it easy to carry and store. 3/4" thick when folded. 48"x60" for double beds.