The 36-round straight detachable staggered row box magazine is wider at the rear than at the front, the extra space allows the tapered 9mm Parabellum cartridges to feed more efficiently. The trapezium design makes the magazine very reliable in dusty environments and sub-zero temperatures, because magazines of parallel-side design are more likely to jam under adverse conditions. The magazine was used post-war by Finland in the m/31 Suomi under the designation m/54, a distinguishing feature of the variation m/55 (made by Lapua) is a steel wire carrying loop mounted at the bottom front edge. The basic design idea of the m/45 magazine was also used for the magazines of the Czech model 23 and model 25 and the French MAS submachine guns.