Machined from 7075-T6 aircraft grade billet aluminum. Matte black hard-coat anodized per Mil 8625 Type 3 Class 2. Precision broached magazine well with beveled feed lips. Machined and engraved to be compatible with 45 and 60 degree short throw fire control selectors such as the BAD_ASS ST 45 Lever. Caliber marking of "Multi" so it can be used with many different caliber uppers. Compatible with all standard AR-10 / .308 components and magazines and most aftermarket parts -- Made to DPMS spec. Upper tension screw behind grip screw (threaded hole with hardware included) to adjust any “slop” out of vertical fit between upper and lower. Contoured trigger finger rests on each side of the magwell.