This bivvy is basically 2 SOL emergency blankets sewn or taped well together. Some people suggested just doing that and using duct tape but it would comprise the size, consistency, and strength; its worth buying the 14$ bivvy. I would suggest buying a fleece blanket as well to line the bag to make it comfortable to sleep with fewer clothes on. also get some duct tape handy in case it tears, but it is made way better than a regular emergency blanket material, so it wont tear unless you roll on some sharp things.
Pros: warms fast and small
This review was written in the old system and had content requirements that are different than reviews written today.