In article , Gary S. wrote:
Good technical description at www.warmlite.com, specifically:
http://www.warmlite.com/vb.htm

This is truly excellent site. The Absolute Truth as me myself have
also observed it.

Last week I myself actually made a sleeping bag whose innest layer is
water-proof eg the Vapor Barrier Layer is in-built. Notice the
approriate X-massy color schema. I pretty sure that this 1200 gram
bag will suffice at -30C. Unfortunately it is only -7C here in
Helsinki.
http://www.kolumbus.fi/timo.noko/pussi.jpg