KATHRYN M Sorry I didn't answer all of your questions: there is no foot vent and the bivy is great in colder weather (zipped tight with a good sleeping bag is OK, but I never tried it at less than about 38 degrees). The big foot box kept my feet comfortable in hot weather, but a foot vent would have given a nice cross flow of air.

KATHRYN M I bought this bivy, even with so many cheaper ones available, because it was the best made with the best material and most comfortable shape. I bought a different brand of bivy for my brother because of his tall height. Even though I still feel that the Black Diamond (BD) is the sturdiest and best made, my brother's has an air vent behind the head space, which is a great idea. Bivies do get hot in hot weather.Black Diamond's taller foot box leaves alot of room for air and free foot movement, but a head vent would have made it an even better product. Even with the front window unzipped, it gets warm. The entrance hole on my brother's bivy zips at least half way down the front for easier access and lots more air, and a tall person can look out with his head at the top end. On the BDthe viewing area starts a bit over 2 feet down. I'm short so that's OK. I still would go with the BD, but its a close call. Hope that helps.