The Fortis Standard Castle Nut is manufactured from a solid piece of billet aircraft grade aluminum that offers a significant weight reduction to your castle nut. If you're trying to save ounces, this is a great way, but without sacrificing durability. The castle nut will fit onto mil-spec buffer tubes and quickly upgrade the form and function of your build. The standard castle nuts only come in black. FeaturesMaterial: Aircraft Grade 7075-T6 AluminumWeight: 5.5gYou will need a standard stock wrench to installType III Hardcoat Anodize