The Lone Wolf Arms AlphaWolf Barrel for Gen 3 / 4 Glock 21 Pistols is a pre-fit, drop-in replacement handgun barrel featuring CNC-machined 416 stainless steel construction. The glass bead, satin exterior finish offers smooth and consistent performance, while the button-rifled bore features a standard crown for reliable accuracy. Designed for use with lead, plated, and jacketed ammunition. Drop-in design. No gunsmithing required. Made in USA.