I purchased this item to add comfort to a form mattress previously purchased for a cal king in our guest room. The fiberbed does not fit the full width of the mattress, but it is comfortable. I am considering adding a mattress cover just to keep it in place under the sheets. We have not had any guests just yet so I can not rate the overall comfort yet, but so far it appears to be adding the height I needed. As usual the delivery was prompt.