Got the Montbell Bivy RyanF suggested to me this Friday when up at the flagship store with some family. Going to do some modifications to it but I'm hoping it will work as my tarpless shelter. Of course I couldn't resist giving it a test run against my Adventure medical thermolite bivy sack. $20 vs $110 shouldn't be a competition but we all know that price does not equal performance. I've certainly been happen enough with the emergency bivy to keep it around and use it a few times when I don't feel like bringing my 4lbs+ tent.
I don't own any summer bags yet, just a Marmot Sawtooth 15 degree down bag. In the summer it's HOT and the other night was no exception. I usually sweat in the bag, causing enough condensation to pool and wet the sleeping bag's shell due to the bivy not breathing. Much to my happiness I woke up dry in the Montbell bivy. Conditions were the same as normal: warm ambient temps, low humidity, face breathing outside the bivy, sleeping bag half unziped, and sleeping pad inside the bivy and outside the bag. Obviously one trial does not equal sucess but it's a promising start. Sleeping pad was also different than normal, now a cut down (19" tapering to 14" and 26" long) blue pad vs full length. Bag showed no cuts or scratches after the night. Aside from a little dirt it still looked new even with no ground cloth.
What we ULers all care about is weight right? And size matters too. Well I don't have an actual weight to list yet as I just use the scales at work and haven't taken it in there. Claimed weight is 6.3oz (178.6g) and I expect it to be close. Regular bag size is small. I'm 5'11" and 155lbs. The bag is *just* big enough for me lengthwise when all tightened up. If you are any bigger than me or want to store any significant gear in the bivy you are going to need the wide and long model. Packed size is tiny. My wife and mom remarked I'd never get the bivy back it's tiny stuff sack but it went in easily. For day trips I'll carry the sack stuffed, otherwise I'll pack my sleeping bag into the bivy for another line of defense. It packs to about half the size of the thermolite bivy.
Overall I'm pleased with the products claims and initial results. It's very light and breathable while keeping me and my sleeping bag protected. After I finish my modifications I'll do a more extensive rain/hose test of the waterproofness.
Breeze Dry-Tec U.L. Sleeping Bag Cover-
• Fully seam taped
• 2-layer Breeze Dry-Tec™ construction
• Air-permeable water-proof breathable material
• 12-denier micro rip-stop nylon shell
• Max Dimension 88.6" x 33.1"
• Draw cord around the face
[Weight] 6.3 oz.
[Stuffed Size] 3.5" x 2" x 7"