We needed a king-sized solution in a house built before beds were that big! Getting mattresses and box springs up the switchback stairs is next to impossible, so we went with a custom-built king-sized captain's bed and a pair of long twin memory foam mattresses. They do have a kind of unpleasant smell when you unpack them but it dissipated for the most part rather quickly (see below) The arrived in a manageable compressed state and expanded just as stated. We covered them with the "king maker" pillowtop (see my other reviews) to make sure we wouldn't feel the gap, but these do not have the "piping" around the edge like a standard mattress and they do not shift around on the wooden box bed at all, so we probably could have done without that, and in fact the mattresses are a snug fit on the bed so there's a slight rise where the "king maker"'s wedge doesn't quite fit between them. These are good mattresses if you like a firm surface. Movement does not transfer to the other occupant as with a standard mattress so they are probably good for restless/light sleepers. Only con is if you end up face down without a pillow there is still (a few months later) a slight remnant of that odor remains, I'm not sure if it's from the king maker or the mattress. We will not be using the bed for a few weeks coming up, so I think we'll try airing all the pieces again with no covers to see if that helps. All-in-all, a good bargain, a good night's sleep.