Montbell Breeze dry-tecThe tiny tot bivy
This little guy will fit into the palm of your hands providing you protection against the elements. Out of its tiny stuff sack comes alot of material: its frankly amazing. The nylon seems thin but strong as does the drytec laminate. I would still be careful with it like any piece of UL gear there has been a reduction in durability in order to save weight. The breeze dry seems to be working, I've slept outside a couple of times with minor condensation on the inside. Its quite comfortable with the top open how ever with it closed the night could be a long one due to breathability and there isn't much room to move around inside: the bivy moves with you which is nice because the air hole is always right in front but it can also be confining. I suggest bringing a small tarp to put over your head in order to avoid closing it up so tight and so water doesn't run into the top opening.
I would't suggest this in a super rainy environment unless you are just using it as a bag cover inside your tent. For occasional storms and moderate weather its perfect.