AMK 2.0 bivvy
The main problem with this bag is that it doesn't breathe really well. It has gaps between velcro closures but those don't seem to vent enough to prevent condensation from forming. Although it is warm enough for the average 50 degree evening, if I close it up over my head condensation accumulates inside and later in the morning it becomes very clammy inside.
Again, the AMK bivvy is an *emergency* bag not intended for comfort...it is meant to keep you alive pending rescue were you lost or injured. Reflecting body heat and keeping you from becoming hypothermic in cold weather, maintaining body heat to avoid shock from a traumatic injury, shelter from wet conditions, etc, all purposes which I think it can answer quite well. If you intend to use it for ultra-lightweight hiking and backpacking, then my suggestion is keep your head out of bag and wear a knit cap.
Often I'll just use a ground cover such as a cheap plastic poncho with a USGI wool blanket for a comfort pad.
Shelter: 5 X 7 tarp, poncho ground cloth, AMK bivvy, wool GI blanket
On a couple of outings my clothes [cotton] got damp in the bag and I started to shiver so I pulled the wool blanket into the bag and was instantly warm. The wool sopped up the moisture and of course wool stays warm(er) even when wet, so it got me through the night just fine. I've thought about adding a fleece liner, but concerned that will just become saturated as well, and then that's heading back into weight and bulk...
On one outing a friend used AMK's lighter 3.5 oz. EMERGENCY BIVVY. Those are made out of a tougher material than the usual mylar emergency sleeping bag you can buy. It's reflective silver on the inside, and bright orange exterior with instructions for survival, rescue, and signalling imprinted upon it. I have also noticed that the EMERGENCY BIVVY compacts down into a pouch about half the size of mine. He reported condensation problems as well, but, I repeat again, it's intended as a survival bag, i.e., not for comfort.
After using it a few times and concerned about the condensation, I wrote to AMK to inquire about the condensation problems and here is their response:
"The version you have is the newest version of the bivvy (the 'SOL
Thermal Bivvy'). We got rid of the foot vent, because it added complexity to the
sewing pattern with no real benefit - extensive real world testing showed us
that the foot vent didn't reduce condensation by any noticeable amount. The best
way to avoid condensation with the bivvy is to keep the side vents open. By
design, the fabric is not breathable, since this is primarily an emergency
product whose main attributes are that it is totally waterproof and windproof -
as a result, condensation is a fairly inevitable result when using the product.
Let me know if you have any further questions, and thanks for your purchase!
Product Marketing Specialist
Adventure Medical Kits
Bottom line: AMK's emergency bivvy's are meant for emergency use. Yes, they can suffice for minimal pack gear. Be aware you may have condensation problems and be prepared to get up and re-warm/dry out next to a fire or towel off with your shemagh. Otherwise it should work fine. I will definitely use mine again, following those provisos, as the weight trade off is too good to pass up.
Now, a friend of mine [JASONHCC / BCUSA forum review: Bushcraft U.S.A. AMK SOL Escape-Bivvy ] has purchased AMK's latest emergency bivvy model, the Adventure Medical Kits "Escape bivvy" and he reports no condensation problems whatsoever. He has also purchased the very recently introduced olive drab model, a useful color for more tactical applications. I have not tested the Escape, and cannot validate his observations, but he is an expert woodsman and I trust and value his opinions. I may have to purchase one of these improved models for my own kit at some point in the future and relegate the old bivvy to a day pack kit or emergency vehicle bag.
If you are interested in AMK's products, visit their website at Adventure Medical Kits.com. AMK offers a complete line of well designed, quality made, medical and survival related products for outdoors men and women which can be viewed on their excellent website. Locally a good selection of AMK gear is available at SLO CAMP N PACK. The store staff is very knowledgeable and can assist you in selecting useful gear for the trail.
Safe Hiking Trails!