Note to future buyers: Check before you open.  I ordered a Firm mattress, and received a Medium. Luckily I read the reviews and realized that could be a problem, and checked before I opened it. If you don't realize until after it expands, I imagine it would be near impossible to get back in the box. But now my little 5-foot-4-inch self is having to lug this nearly 4 foot, 96 pound box to the FedEx store to return it. And I pray I get my money back.  :(