The Davidson Defense AR-15 Billet 9mm Upper Receiver is a stripped upper receiver designed for use with 9mm AR-15 builds. It is machined from a solid billet of 7075-T6 aluminum and features a Picatinny rail for mounting optics and other accessories. The receiver is compatible with Glock magazines and features a slickside design with an enlarged ejection port door. The design enhances the upper receiver's reliability and ease of use. The Recoil Technologies Billet 9mm Upper Receiver is a popular choice for those looking to build a reliable and high-performing 9mm AR-15.