AR15 stripped lower is machined from 7075-T6 billet aluminum. The contour is fully machined leaving no flash marks from the forging and we take extra care when machining our receivers resulting in tolerances that are tighter and fits that are better than other receivers. We adhere to mil-spec tolerances to ensure that our lower remains compatible with any quality aftermarket parts you can find. After the machining process is complete the lowers are checked for quality and shipped off to our finishing facility for hard coat anodizing.