Auto Ordnance manufactured this parkerized steel magazine for the Thompson semi-automatic carbine.
The maximum capacity for this magazine is 10 rounds. Will only hold .45 Automatic Colt Pistol rounds. The steel housing on this magazine has been parkerized for resisteance towards wear and corrosion.
Auto-Ordnance was a U.S. arms development firm founded by retired Colonel John T. Thompson of the U.S. Army Ordnance Department in 1916.