Extremely Rare WWII United Defense Supply Corporation M42 Machine Gun Magazine

This is an extremely rare WWII United Defense Supply Corp M42 Machine Gun 9mm magazine. The M42 (UD-42) submachine gun was designed by Carl G. Swebilius of the High Standard Manufacturing Company in 1940, afterwhich further development was handled by the United Defense Supply Corporation founded by Pope and Jackson of the British Purchasing Commission. It was only produced from 1942 by United Defense Supply Corp. as a possible replacement for the Thompson SMG with about 15,000 produced in the last three years of World War. The design is based on the standard Thompson .45 ACP magazine with the same spine dimensions but with a reduced magazine tube for 9mm ammuntion. A very rare find indeed!