I had heard of “mattress in a box” but this was my first experience of buying this kind of mattress.   It arrived in a 12” x 12” x 5’ approx cardboard box.   It had been compressed and rolled in plastic to achieve the shipping size.   It was fascinating watching it expand as packaging was removed, into a full queen size mattress 12” thick, comprising 9” of packet springs with a 3” topping of memory gel foam.   I left it a few hours to stabilize before putting it to the test.   This mattress is very supportive and comfortable, resulting in one of the best nights sleep I have experienced recently.   FedEx delivered it to my front door and it took 2 of us to carry it up to the bedroom - it is around 80lbs - so be prepared.