These forged lowers are quality made using 7075-T6 aluminum and are marked "MULTI" for caliber. Built with a Palmetto State Armory Classic Lower Parts Kit and fitted with a Magpul BTR Pistol Brace and Classic A2 Grip in black. The Magpul BTR is an AR arm brace designed to improve the single-handed employment of large-format pistols. The BTR utilizes Magpul design and engineering to offer a stabilizing accessory with a robust feature set and trusted Magpul quality. With classic Magpul aesthetics, the BTR is compatible with Mil-Spec carbine receiver extensions and employs a simplified, durable, and easy-to-use adjustment mechanism. An integrated QD cup and M-LOK compatible slot provide ambidextrous sling mounting options and enable stabilizing sling tension to be applied, drastically increasing single-handed control of the firearm. With a straightforward design and Magpul innovation, the BTR is a simple solution to improving your AR pistol. Made in the USA.