Military Issue Water Canteen
Two quarts, Army issue, OD Green. Not a whole lot else to say about this water canteen. Except that two quarts of water isn't really enough for a long, strenuous hike or desert offensive. Two quarts of whiskey might be enough for those things though.
The military canteen has a collapsible interior and outer cover/carry pouch with an adjustable sling. Its drinking cap is gas mask compatible.