I ordered a Twin XL. The box was very heavy, and the glue holding the box closed was impenetrable. The mattress grew to 13 instead of 14, but I knew that was a possibility.  The edge support isnt firm.  I wouldnt recommend sitting on the edge of the bed.  You can sit on the mattress and hang your legs off the side. I have slept on this bed numerous times, and it is very comfortable.