The XD OSP Slide Assembly includes an OSP-cut slide assembly for an XD 4a ^2 9mm pistol along with a Springfield Micro footprint optics-mounting plate. It is designed to convert an XD 4a ^2 9mm to an XD 4a ^2 9mm OSP, while utilizing the original pistol's barrel and recoil spring system. With this assembly, you can easily swap out the slide on your 4a ^2 9mm pistol to gain OSP optics-mounting capabilities.