Actually, there is a foam of some kind inside that expands and pulls air
inside. When you open the valve and squeeze the foam, the air goes
out...and you lock it out by closing the valve again thereby making a
smaller package. The concept has been around for many years...first being
used (to my recollection) for sleeping pads for backpacking. They work very
well.

Barry


"Dave Van" wrote in message
k.net...

"Don Freeman" wrote in message
...

"Dave Van" wrote in message
link.net...

"PaddlingPair" wrote in message
...
Finally my wife surprised me with the Sealine
Thermorest thigh support. It is Wonderful and worth every penny (to
me
at least) of the $40. It is infinitely adjustable and because it is
self
inflating you don't have to take it out and blow it up!


Self inflating? What does that mean?

Assuming that it is the same as self inflating mattreses, the shell has
some
sort of shape retention that "remembers" the shape it should be when
filled.
As it expands from the tension of the material it sucks the air in
through
a
valve. When it is full then you close the valve so the the air does not
escape when your weight puts pressure on it. To deflate you open the
valve,
squeeze the air out and shut the valve before the air can get sucked back
in.


Sounds close to what I was thinking it might be. I was thinking that
there
was some kind of open cell urethane foam cushion inside that gave it a
full
shape.