Engineered to improve tactile trigger reset of your M&P pistol Serves as a failsafe in the unlikely event of a trigger return spring breakage Keeps the trigger bar properly positioned under the sear and allowing the user to manually manipulate the trigger forward between shots This product works in Smith & Wesson M&P 9mm, .357 Sig and .40 S&W models only that DO NOT INCLUDE a thumb safety, Magazine Disconnect or the Internal Locking System PRODUCT WILL NOT WORK IN VTAC VARIANT DUE TO CHANGE IN SEAR HOUSING BLOCK CONFIGURATION Precision machined and heat treated to out rigid quality control specifications with the utmost durability and long Mfg: Apex Tactical Specialties Inc