It's hard to see in the single photo provided, but there's no entry/exit closure like a zipper or velcro, except going out the top of the bag. That was a deal breaker for me. Everything else about the sleeping bag cover was great and would have been perfect, except for that one detail. I was sorry to have to return it.

I bought this cover for a trip to the Yukon Territory where I didn't know exaclty what our sleeping conditions would be. I get cold very easily (we're talking frozen to the bone when the temp is right at freezing in a bag rated for 0). Point is, I'm a complete wuss in the cold and was worried about freezing, and getting my bag wet and dirty. I only used this cover a couple of times, and the first time I pulled it out of the stuff sack, I admit I was afraid of not being able to get all that material back into that tiny space (it was NO problem), it not only kept my bag clean and dry, but also added a little bit of warmth-exaclty what I wanted. I highly recommend this cover, but like the other reviewer posted, it is probably best if you are sleeping in a tent, since there is nothing to cover your face.

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.