Semi-auto lower receiver lets you build a dedicated 9mm AR. Magazine well is machined to accept Metalform style 9mm magazines. Eliminates the need for a separate conversion block and the reliability problems that can result from converting a standard .223/5.56mm lower with add-on parts. Comes with feed ramp, bolt catch, and ejector all designed for best function with the 9mm pistol cartridge. Plus, the flush-fit mag well gives your gun a clean, uncluttered look. All holes, inletting, and pin locations have been machined to final dimensions. Add the trigger group, buttstock, and 9mm buffer/spring of your choice. Machined from high-grade 7075 T6 aluminum. Hardcoat anodized finish.