Mattress In A Box

I am absolutely amazed by Adelaide's mattress in a box. We bought her a twin bed. We bought it on-line from Wal-Mart and had it shipped to the store. We pick it up Friday and they pull out 2 boxes and that was it.
I asked "where is the mattress?"
To which they said "it's in this box."
"???" was the only response I could come up with as I had an extremely dumbfounded look on my face.
We pulled it out of the box and oh my! The mattress had been rolled up and vacuum sealed. I was blown away when we opened it up and found an actual twin mattress in this little box. It is very comfy and Adelaide has been playing on it all day.
The box...

The mattress...