Shortly thereafter, a second patent was applied for by Theodore Eickhoff on June 20, 1920, U.S. Patent # 1,365,234 (January 11, 1921) granted. This design refined the design into what we are familiar with today. The magazine exhibited a one piece formed sheet metal follower and a floor plate that is held in place by a set of channels in the bottom of the magazine body. These magazines are slightly shorter in overall height than later productions and were serial numbered. These magazines will fit Model of 1919 Serial Numbers 11-40. Some of these magazines were shipped with very early production Colt Thompsons.

PROTOTYPE XX BOX MAGAZINES. THESE MAGS WERE SERIAL NUMBERED ON THE 0UTSIDE OF THE BACKSTRAP