Produced in Boston, Mass, the LM-4 was designed expressly as a backup weapon, placing as much firepower in a compact space as possible. Chambered for 45 ACP and loading from a 5-round detachable magazine, the pistol is manually operated, extracting on the forward movement of the slide, chambering on the rearward, and firing in double action mode. Total measurements are 5 1/4" long, 3 3/4" tall and 1 1/4" wide across the grips. Marked "CAL. .45 ACP" and "STD. MIL. SPEC. CTG. ONLY" on the right side of the slide, "MOD. LM-4 / PATENTS PENDING" and "SEMMERLING CORP. / BOSTON, MASS." on the left. Smooth trigger, smooth black walnut grips and matte finish with polished slide sides and right side plate. With a copy of a 1981 letter from the President of Semmerling, describing a pistol 2 numbers higher as being produced in September 1977, using an early style lightweight frame, and stating that while such a weapon could be shot, it was, in the President's opinion, "too valuable to carry".