The size of the box is approx three feet high and about two feet deep. Quite heavy but not sure of exact weight rating. The mattress is vacuum packed inside two bags.
It allows each persons body to sink in individually and the mattress keeps its shape. It doesn't sink in or cause you to pull apart. I have also noticed that it keeeps its shape perfectly. My husband is disabled and is in bed about 12 to 15 hours every day ( which is why we bought another mattress) and the mattress looks the same even after using it for four months. Highly recommend!
No sagging issues what so ever. I'm at 220lbs 6'2. Mine sits on a heavy duty platform frame. Best sleep I've ever had. Firm but completely comfortable. I fall asleep in less than 3 minutes.