Grayguns unique step-tapered design and unmatched surface finish afford easy installation with optimum recoil spring support. Proper spring support ensures maximum spring life and smooth cycling. Grayguns'fat guide rods are designed to optimally support factory SIG Sauer and Grayguns custom multi-strand springs for maximum service life and smooth, reliable function. Being made to the maximum nominal diameter to fit each pistol perfectly, fat rods also eliminate the possibility of coil-jumping and damage when used with correctly-selected after-market single-strand recoil springs. Includes a 15 lb recoil spring. FeaturesEnsures smooth cycling of the pistol slideSuper Black finishEach guide rod is carefully polished and inspectedProper sizing to ensure the guide rod spring stays in place