The Armaspec Self-Retention Castle Nut is a lightweight AR-15 component designed to simplify buffer tube installation while improving long-term retention. Its self-retention thread design uses patented locking geometry to eliminate the need for staking or thread locker, maintaining a secure fit under repeated use. Machined from 7075-T6 aluminum, the structure offers a high strength-to-weight ratio suitable for performance-driven, lightweight rifle builds. A hardcoat anodized olive drab green finish provides increased resistance to wear and corrosion. This item is made in the USA. Features: Self-retention thread geometry with no staking or thread locker required Precision-fit for improved retention and minimal movement Constructed from 7075-T6 aluminum Hardcoat anodized for corrosion and abrasion resistance Installs without special tools Specifications: Color: Black, FDE and OD Green Finish: Hardcoat Anodized Material: Aluminum - 7075-T6