Emergency Rescue Bivy, New product, 15% off for Backpacklinglight readers

if it’s waterproof on the top, isn’t there condensation inside?

Jerry, did you read all of the post?

What are the dimensions of a tightly packed/bundled bivy?

I did read all of the post but was a little unclear

I guess it’s just intended for emergency so yes, you would get condensation on the inside

It also says it prevents radiative heat loss but it doesn’t appear to be reflective, like aluminized Mylar

It would be considered a vapor barrier bag for emergencies, overnight use or winter backpacking?

No Mylar, but there is still some radiant heat capture from most any fabric.

It is purposely not breathable, for those short term situations where every calorie of heat is needed and a breathable fabric would drain some energy in the water vapor transfer. It is  similar to single use emergency bivys, but for repeated use. *

It would work as a vapor barrier liner. Sizing is generous and fits over a pad and sleeping bag. Might be able to shave an ounce or two if  sized smaller as a stand alone VBL.

Anecdotal use- TNSAR found a lost Snowboarder on the backside of Alpine Meadows Ski Resort walking down a knee deep stream heading toward Auburn a 100 miles away. (easier to walk in the stream than the thigh deep powder snow, easier to walk downhill than back up the way he came.). 17 below zero F.  Multiple layers of thick cotton clothes. When searchers found him he was shivering. They stuck him in the silnylon bag and he warmed enough to stop shivering. Helicopter came with pizza, sleeping bags and tent. Rider ended up having a grand adventure complete with dinner and a chopper flight.

*I made a big batch of a DWR breathable version in subdued colors for those looking for a quilt or sleeping bag cover to keep out drafts, snow and dirt. https://bivysack.com/shop/ols/products/bivysack-drawcord-closure-347893c1-f915-4f24-8ca8-4c945cc42174

“What are the dimensions of a tightly packed/bundled bivy?”

Here is one in the stuff sack. (3.5×2.5×6″) I can squeeze it further to about half the thickness of this photo. (2×2.5×6″)

Thank you.