Smith & Wesson Hammer Assembly Spurred S&W 4003TSW, 4006TSW, 4563TSW, 4566TSW, 5903TSW, 5906TSW, 1006, 1066, 3904, 3906, 539, 4505, 4506, 4566, 4596, 559, 5903, 5903SSV, 5904, 5906, 5967, 909, 910,

Factory replacement parts are manufactured to the exact same specifications and tolerances and use the same manufacturing materials as the original parts. Some parts may require installation by a qualified gunsmith.