DPM 4.4in Barrel Full Size Mechanical Recoil Reduction System Sig Sauer P220 Nitron & Legion Stainless. The third spring which is contained within the rod controls the movement of the slide so it never rams on the frame. The third spring which is contained within the rod controls the movement of the slide so it never rams on the frame. The system includes one spring plug and two different external springs. The spring plug must always be installed when the DPM Recoil Rod and springs are used. 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 positions (slide on the battery) according his/hers personal standards. Specifications for DPM 4.4in Barrel Full Size Mechanical Recoil Reduction System: Manufacturer: DPM Color: Stainless Fabric/Material: Stainess Steel Gun Make: SIG Sauer Gun Model: SIG Sauer P220 Features of DPM 4.4in Barrel Full Size 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 4.4in Barrel Full Size Mechanical Recoil Reduction System What firearm models does the manufacturer say DPM 4.4in Barrel Full Size Mechanical Recoil Reduction System is compatible with? The manufacturer suggests that DPM 4.4in Barrel Full Size Mechanical Recoil Reduction System is compatible with SIG Sauer P220DPM MS-SI/1: 4.4in Barrel Full Size Mechanical Recoil Reduction System Sig Sauer P220 Nitron & Legion Stainless