The Aero Precision M4E1 Stripped Lower is a bare, unassembled lower receiver for AR-15 rifles, designed as the foundation for custom builds. As a stripped lower, it does not include internal components such as the trigger, safety selector, or buffer tube, allowing builders to customize their rifle by selecting and installing parts to their exact preferences. This serialized component is considered the firearm under U.S. law and must be transferred through a licensed dealer. Machined from 7075-T6 aluminum, the M4E1 Stripped Lower combines the ruggedness of a forged lower with enhanced features for easier assembly and improved functionality. It includes an integrated trigger guard for added durability and a threaded bolt catch pin for simplified installation. The lower is precision-machined to Mil-Spec standards for compatibility with a wide range of AR-15 components and features a Type III hard anodized finish for corrosion resistance and long-term durability. With its advanced design and high-quality construction, the M4E1 Stripped Lower is an excellent choice for builders seeking a solid and customizable foundation for their AR-15.