The BATTLEARMS XIPHOS dedicated PCC upper was designed to be a lightweight and rugged option when it comes to pistol caliber upper receiver groups. Even though it is matched perfectly with their XIPHOS lower receiver, this upper receiver will work with any MIL-SPEC style 9MM lower receiver. The BAD-PCC-UR is machined out of a solid block of 7075 T6 aircraft grade billet aluminum and has lightweight cuts to remove material where it is not needed, but at the same time retains the structural integrity that you would expect.