User Review: REI Minimalist
Price Paid: $100
This bivy sack is awesome and light. It weighs just over a pound. It is waterproof nylon ripstop material with a nylon coated bottom. It has four zippers so you can keep your arms out and still keep you dry. It has a no see um mesh that covers your face for the bugs.
I used the bag in my snow cave in march of 2011 and it kept my bag dry but there was a little precipitation on the sack, but my bag was dry but I guess that's why you use a synthetic bag over a down bag.