Solid-frame spur-trigger single-action revolver. Chambered for .22 rimfire short. Round barrel 2.25" and 7-shot cylinder is unfluted. Frame nickel-plated brass, with blue or nickel-plated barrel. Bird's-head grips are rosewood. Cylinder pin is removable and used to knock empty cases out of cylinder. Top of barrel marked "O.K." and "J.M. Marlin. New Haven, Conn. U.S.A.". Approximately 1,500 manufactured between 1870 and 1875.