Genuine British Army issue Bivvy / Bivi bag.
Issue MTP Bivi Bag.
Made from MVP that is Moisture Vapour Permiable
Fully waterproof and breathable
Packs down very small
Designed to replace the basha when a low profile is needed
Large enough to take you your sleeping bag and additional kit
Large toggle at the opening so that you can close it up so just your face shows
You can still exit this bag in a hurry if you need to
Can be used on its own when its warm but still raining

These bivvy bag's is fairly big so will accommodate most sleeping bags and sleeping mats with ease. 

Please Note the bivvy bag does not come with a sleeping bag