A quintessential part of the IMSS (Improved Modular Sleep System) the waterproof bivi bag.
These are made in ACU/UCP Camouflage (that wonderful urban camo that blends in with a gravel pit and grandmas couch) as a replacement for the earlier BDU Bivi covers as part of the MSS (Modular Sleep System). The inside is a solid foliage green, and there is a zipper along the side with additional snaps. It can be used in conjunction with one or two of the IMSS sleeping bags.
These are made from goretex, and will therefore offer a small degree of insulation on their own in addition to the waterproof aspect. They will work with most people and fit over most sleeping bags as they are made rather long and large.
The entire system includes two sleeping bags, two stuff sacks, and the bivi cover. All of these components are available separately.
These bags are all in good used condition, and will be free of major defects or holes. They may have some scuffs or dirt, but will still be completely usable.