These are thinner than the old inflatable Lilo, but contain expanding foam rubber inside them. To inflate them you just take the stopper out of the valve and the air rushes in as the foam expands. You can firm up the inflation by blowing if you want to, but usually it is not necessary. But if you have a pin hole it is not obvious until you have gone to lie down. Slowly the air seeps out until your hips meet the ground and you feel very uncomfortable. But as soon as you get off the mattress, it re-inflates! Pins holes can be found by putting the mattress under water. Apply the Stormsure Flexible Repair Adhesive once dry and allow to cure in the normal way. Occasionally I have seen large rips in the mattress, where the foam has been exposed. This might seem to be a disaster. But Stormsure applied over the exposed foam will stop air leaking out through the open cell structure of the foam and keep it airtight. the mattress will have many more year life in it.