The revolutionary Nighthawk Custom Everlast Recoil System uses a flat wire recoil spring, special guide rod, and plug that allows shooters to shoot a minimum of 15,000 rounds before the need to change recoil springs. One of the key benefits is how it handles felt recoil. Normally when the gun is fired and the slide starts to move rearward, the standard recoil spring continues to increase resistance until it is fully compressed. The spring in the new Nighthawk Custom/Bob Marvel Everlast Recoil System maintains a steady, consistent resistance from the time the slide begins moving rearward, all the way through the cycle. The result is a less pronounced muzzle flip. Our guide rods and plugs are Fully Machined™ from a premium-grade 416 stainless steel billet, making these the finest 1911 parts on the market. With a one-piece guide rod, there are no threads to work loose and compromise your firearm. The backside of the guide rod has been beveled to prevent contact with the lower lugs.