That a king size mattress can be shipped in a box, is a pretty amazing feat! We unwrapped the mattress, amidst the many layers of packaging and shrink wrapping , and it inflated quickly to 3/4 of it's size, and then over the next couple hours inflates to the full 11 inches. It's a pretty soft mattress, so if I'd tried it out in a store, I probably wouldn't have bought it. Having said that, it does feel comfortable to sleep on, and so far have woken up with no back issues, so hoping it will continue. It certainly is better than the mattress we had, and as this is a vacation home, will be a fine purchase.