WW2 production of this Leather Spare Parts Pouch as issued to for the Thompson Submachine Gun as found in the Thompson Manuals. Originally made in WW1 and designated M1921 for issue for the Browning Automatic Rifle but then issued for a few other weapons. It held spare parts for the particular weapon it was issued for. Made by various manufacturers and all stamped with their name (initials mostly) and dated. These were designed to be carried in one of the Bar Gunners belt pockets and fit perfectly.
This particular one is in un-issued perfect condition and maker manufacturer marked B. L. G. Co. and dated 1942 under the flap on top of the brass ring. Many of these were modified in the field with slits in the back or belt loops to be held on a belt for convenience but the original design is as this one without any modifications.