Ventile was designed a) for wearing in a dry aircraft cockpit, where the pressure changes required a breathable suit, and then b) immersion in the arctic ocean for an hour while the pilot was rescued. WWII ship-launched fighter pilots. Saved many lives. Apologies if you already knew this.
I'm assuming the life saving ability was that once the ventile is saturated, the fabric expand and makes slightly air tight and that this allowed the pilots to trap air in it to keep above water as a sort of flotation device? I noticed it going pretty stiff when wet so wouldn't make swimming easy if still being worn.
I had no idea it was used as a life saver. If it wasn't used for flotation, how did it work?
Yeah the guy didn't mention whether it was an SDP one. I don't know if there are older variants and this may be just that however it is a good start point for me to assess if the jacket suits my needs before splurging big money.