Spike's Tactical Delta Ring Assembly With Nut, Fits AR-15 Rifles, Black SDR100A The Spike's Tactical Delta Ring assembly is fully Mil-Spec and comes ready for you to finish your new upper. The barrel nut is machined from tough chromoly steel" is properly heat treated" and of course completed with a phosphate finish. The weld spring and snap ring are likewise finished in a phosphate finish per Mil-Spec. The delta ring itself is made of Mil-Spec aluminum and features a black anodized finish. Inside the package you'll find everything already installed so you can quickly mount your barrel and get that build one step closer to being finished.