Ron, to share my enthusiasm with others in the forums, I used your Superlight bivy (large) this year on the JMT inside a tarp tent and loved it immensely. The large supports the neo air (even though I returned the neo air and went back to the 1" thick Montbell sleeping pad which I like better). The bivy is great for a whole host of multi-purpose reasons: (a) breaks the wind which seems to easily penetrate a tarp tent and sleeping bag at high altitudes, (b) provides extra ground protection to the sleeping pad against punctures, (c) keeps my body positioned on top of the sleeping pad (which is inside the bivy of course), (d) serves as a light sheet when it's too hot early in the evening to be inside the sleeping bag, rather I just lay on top of the sleeping bag/on top of the sleeping pad/but inside the bivy, (e) and provides about 5-10 degrees extra warmth on top of what the sleeping bag provides. It weighs less having the bivy with a 32 F WM summerlite than taking along instead a 20 F WM sleeping bag and accomplishes the extra warmth as well as the othe functions listed above. On top of that, it takes up less space than the warmer bag too. I highly recommend the bivy to high sierra hikers. I don't have the eVent bottom, but had no problem with my sleeping bag getting condensation wet. The breathable Momentum (is that the fabric used) works just great on top side of bivy.
