These are USGI bivy covers to the US Army 5 piece sleep system. The bivy covers allow the user to stay dry and warm in inclement weather without worry. When used with the patrol and intermediate sleeping bags the user is able to sleep in the open to temperatures as low as -10 degrees. The bivy is lined in Gore-tex and has a full length zipper so that is is easy to get in a out of. When used with just a lightweight sleeping bag it makes for a great way to be able to sleep out in the open when camping or when you want something just for emergencies!