DPM H&K VP9SK Compact Telescopic Recoil System Stainless. The 3 springs of the system are aligned and gradually compressed so as to offer an elastic effect of the slide travel and to control the movementThis system works due to the multi spring intricate rod (3 springs) and controls the functionality of the pistol using more efficient the small internal space of the subcompact pistols. The 3 springs of the system are aligned and gradually compressed so as to offer an elastic effect of the slide travel and to control the movement of the slide so it never rams on the frame. Included with the DPM System are 2 external springs all with different power rates with the longer spring always being the stronger so the user can fine tune the pistol recoil with different type of ammunition according his/hers personal standards. of the slide so it never rams on the frame. Included with the DPM System are 2 external springs all with different power rates with the longer spring always being the stronger so the user can fine tune the pistol recoil with different type of ammunition according his/hers personal standards.EW PRODUCT Specifications for DPM H&K VP9SK Compact Telescopic Recoil System: Manufacturer: DPM Color: Stainless Fabric/Material: Stainess Steel Gun Make: Heckler & Koch Gun Model: Heckler & Koch VP9 SK Package Contents: DPM H&K VP9SK Compact Telescopic Recoil System What firearm models does the manufacturer say DPM H&K VP9SK Compact Telescopic Recoil System is compatible with? The manufacturer says that DPM H&K VP9SK Compact Telescopic Recoil System is compatible with Heckler & Koch VP9 SKDPM MS-H&K/4: H&K VP9SK Compact Telescopic Recoil System Stainless