DPM 2011 5in Bull Barrel Mechanical Recoil Reduction System Black Oxide. The long spacer offers a heavy buffer effect moving to shorter spacers a lighter buffer effect is being noticed. Washers differentiate only the buffer force (slide full open position) and the external springs differentiate only the slide closed position (slide on the battery). The external springs are different in length the long spring is heavy and the short is light so the user can fine tune the pistol on the opening and locking position (slide on the battery) according his/hers personal standards. As lead the evolution of recoil reduction technology products may change versions (new design with different springs with or without plugs washers etc.) without any prior notice. Specifications for DPM 1911-2011 5in Bull Barrel Mechanical Recoil Reduction System: Manufacturer: DPM Fabric/Material: Spring Steel Gun Make: 1911 Platform Gun Model: 1911 Features of DPM 1911-2011 5in Bull Barrel Mechanical Recoil Reduction System Faster follow up shots Improved firing speed Slide and Frame Protection Elimination of jams Significant recoil reduction Better double-tap concentration Better control and greater accuracy Package Contents: DPM 1911-2011 5in Bull Barrel Mechanical Recoil Reduction System What firearm models does the manufacturer say DPM 1911-2011 5in Bull Barrel Mechanical Recoil Reduction System is compatible with? The manufacturer says that DPM 1911-2011 5in Bull Barrel Mechanical Recoil Reduction System is compatible with 1911DPM MS-1911/A1-5-ER-SE: 1911-2011 5in Bull Barrel Mechanical Recoil Reduction System Black Oxide