May be difficult to install at first buy works likr a charm - DPM Heckler & Koch VP-40 & SFP-40 Mechanical Recoil Reduction System

I agree with the previous rater; this item may be difficult to install at first. I think that one star rating may have been in frustration. But one this is installed properly, your KH Vp9’s recoil is so much easier to manage. My accuracy has improved significantly since I’ve installed this cool shooting system. I can rapid fire 10 rounds in a 4 inch group at 15 yards. It seems like the gun just snap itself back on target effortlessly. You just gotta her past the initial frustration of installing the spring. It gets easier to install from then on.