Recently we picked up several Viet Nam era 5qt collapsible canteens from military surplus and we've been thrilled with them. Not only do they hold five quarts (1.25 gallons) but they also hold air and can be used as a pillow and as an emergency flotation device. Versatile gear is invaluable! I am going to need to figure out a way to be able to use my Sawyer water filter with these collapsible canteens and I don't think that is going to be difficult a task.
USMC FILBE Hydration Carrier is made in the USA and issued by the US Government to the United States Marine Corps. This particular hydration carrier is manufactured by Propper International and is part of the FILBE family of gear used by the United States Marine Corps. FILBE is an acronym that stands for Family of Improved Load Bearing Equipment (FILBE).