Adding a horizontal extension to the hammer provides a larger contact surface and outstanding grip and control. Especially useful on scoped firearms where clearance can become an issue, GrovTec hammer extensions are made with the finest materials and finish in the industry. It can be mounted on the right or left side. Each hammer extension is specific to the firearms it fits. Do not use any hammer extension on a firearm not directly specified in the hammer extension's fit list. For All Marlin Lever Actions made in 1983 & later including 39A, 39M, 1894, 1894C, 1895S, 336C, 336T, 375, 444S, Glenfield 30A.