Developed in the 1930s, the sleeve pistol of Elmer Carlstrom of Chicago, Illinois uses a mechanism similar to many pen guns of the era, with a screw-mounted smoothbore barrel and a pre-cocked spring loaded striker for firing. Unlike a pen gun, the Carlstrom is normally equipped with a rifled barrel, a steel reinforced leather base, which straps to the underside of the user's forearm, and a light cord that attaches to the trigger mechanism; depending on user preference, this line can be secured to a ring on the finger and automatically discharged when the appropriate hand is flipped upward, attached to a dummy cuff button to be pulled by the off-hand like this example, or other imaginative combinations. This example has been fitted with a smoothbore barrel that is choked at the muzzle, possibly the result of the original barrel being bored out, and appears to be configured for firing blanks or gas cartridges of some type. The left side of the metal plate that secures the pistol to the leather base is marked "PATENTED E. CARLSTROM CHICAGO/4852 S.MAY ST./U.S.A.", with the right side additionally marked "1229", and there is knurling on the cocking knob and barrel ring. Fitted at the front and rear of the base are blue and white cloth straps, with a pair of buttons on the front and a claw buckle on the rear.