This tube was made specifically to match up to the Tailhook Mod 1 pistol brace ideal diameter. The user can install the Tailhook brace anywhere along the tube as desired. The overall length is 9" and does not include buffer, spring, castle nut or end plate. It is a tube only. It does accept standard carbine length buffer and spring. Features anti rotation slot for standard end plates. Anodized finish. Made in the USA.