In reply to Tyler: HyVent is a coating applied (sprayed onto the fabric) which is why it's less breathable than gore, event etc
However, HyVent Alpha used in higher quality products like the makalu, plasma thermal etc is made by spraying the same coating to a non-stick surface, then being peeled off and physically applied to the fabric.
It's hard to read about HyVent online as there is nothing to read about anywhere, I got this info last week from som TNF reps