I slept in the rain for a night; it rained through most of the night, switching from sprinkles to heavy rain many times. It was windy as well during this summer thunderstorm.I kept very warm and dry, however my old school down mummy sleeping bag had 4 small nickle/quarter-sized water spots on the chest area. Not sure if it's condensation or a leak but it was not a problem and didn't affect my experience.I took away a star because I don't like the mummy bag concept. It feels restrictive and I get kinda claustrophobic. I did however, have a sleeping pad inside.But if you don't mind the mummy bag design, this is a great one and I recommend it.This Bivvy looks and feels amazing. In the Army with our sleep system we don’t get issued OCP/Multicam bivvies we get UCP from over 10 years ago and it’s nice to finally get a bivvy that matches all my OCP GearThis item met all of my expectations.Haven't used it yet next month but looking it over it's excellent quality and is better than I expected totally satisfiedI bought this as an ultralight replacement for my MSS Bivy, which weighs 1 lb 13 oz. This is advertised as 4.8 oz, when in reality, it is 2lbs 3oz. Heavier than my MSS Bivy. It might be a great bivy but I never took it out of the sack. Seller should correct the ad please. Returning it.I have used the Bivi Sack for years doing my survival camping and backpacking. It allows to replace your typical tent with out any concerns for exposure to the environment regardless of weather conditions. I was in rain in 22 degree F. and I remained warm and dry. So, purchasing another will now allow me to introduce it to future clients without having to carry a tent for them and have them experience it as well. I do love it.