S&W REVOLVER 629, 686, 586, 627, 66, 67, 696, 17, 19, 657, 610, 625, 29, 27 and new caliber .50. All new models with drilled and tapped frame for S&W scope. Overall height of the rear sight to replace has to be between 10-10.5 mm The revolver has to be suitable to accept S&W scope (all new drilled and tapped frame) After having disassembled the standard sight, the TXT has to be fitted on the gun by means of two screws supplied into the blister pack. RED DOT NOT INCLUDED