Fortis Manufacturing, Inc., Castle Nut, Black, Anodized Finish, Mil Spec WARNING: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov Material: Aircraft Grade 7075-T6 Aluminum Weight: 0.2 oz! You will need a standard stock wrench to install Type III Hardcoat Anodize Made in the USA! 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.