how do self inflating mattress work?

Question

say the principle clearly

Answer 1

For camping, usually they are a very soft open cell foam that has a skin or bladder around it. You open the valve and roll it tightly and most of the air goes out and it is compact. If you open the valve and unroll it, the foam expands and stretches out the skin and when you close the valve it stays "inflated".

Answer 2

Other self-inflating mattresses tell them their work is valuable and have ten to twelve awards shows per year broadcast on network television while all the regular mattresses are looking for something better to watch on TV.

Or maybe the Oscars were on last night...