This factory replacement, P320 RXP X-series Stainless Steel slide assembly fits X-Compact and Sub-Compact size (X-series ) grip modules. It accommodates the 3.6" barrel. This slide comes with the Romeo1Pro mounted on top, ready for use and is equipped with suppressor height, X-ray night sights. *Note, only for use on 9mm/ .357SIG / .40S&W firing control units (FCU). It will not function with a .45 ACP FCU.