This is a large canteen and general purpose pouch that was used by the US Air Force. The pouch fits a USGI 1 quart canteen with some room to spare. However, it will not fit a 2 quart canteen. The pouch is great for bulkier items. The buckled flap secures the items.
This pouch comes as a part of the Defensor Fortis Load Carrying System Kit (DFLCS).