This is the standard Bivy Bag (Bivouac) that will fit the smallest to the largest Wiggy's sleeping bags & sleeping bag systems.
IT IS WATERPROOF. You may have seen the same type of product offered in military after market catalogs for as high as $230.00. I have been supplying mine to the military for 10 years.
Regardless of common belief, Bivi Bags DO NOT add to the temperature ratings of sleeping bags. The job of the Bivi Bag is to protect the user from rain, snow and wind when a tent is out of the question. Understand that ALL Bivi Bags will collect moisture on the inside.