Picked up these Whirl-Pak water bags from 5COL a while back. They are made by Nasco. I bought these with own money. My goal with these was to stash several packs of these all over the load out. They are 1 liter each, food grade plastic, no odor. They weigh next to nothing. Can be used for water collection/purification/storage or have multi use as food bags, berry collecting bags, solar water sterilization , (link 2 - SODIS) etc. 4mm plastic construction (sonic welded) and can stand on end. 6 of these bags, folded up take up approx 4" x 5" x 1/8" your kit. (very little room). You can literally tuck one pack (6 bags) in each pocket and have upwards of 30+ liters water storage capacity (unfilled) in one jacket..... These bags are sterile (originally made for lab use). There is a perforated tear off on each bag, this has to come off to use the bag. Once opened the bag has two plastic wrapped aluminum tie offs to seal the bag (roll bag up, secure tabs). There is also a small space on the bag to write on. filled with creek water. This water from this creek has made me ill before. added two PRISTINE tabs, rolled up the bag and secured the tabs. Now the tabs are not 100% secure, not like a container with a screw on lid. However, i was able to gently shake the bag to mix the PRISTINE tabs. Then I let it settle for 30 minutes. (one could also simply place the Whirl-Pak filled with water in the sun fro 5 - 6 hours) solar sterilization after 30 minutes (water treatment tabs) or 5-6 hours (solar sterilize) time to hydrate. Unroll the bag and you have fresh clean sterile water. You can roll up the bag if you still have water in it and carry it like a water bottle. pretty durable bags, Even after much usage if they can no longer hold water (pinholes from wear and tear), they can still be used to hold gather/store food, or collect / store tinder etc. 10/10 product.