Upgrade your full-size XD handgun with the new XD OSP (Optical Sight Pistol) Slide Assembly and Kit options. These 4 9mm kits and assemblies provide original XD owners OSP capabilities as well as the ability to convert certain XD models to a full-size 4 9mm configuration. The slide assemblies featuring included cover plates are cut to accept OSP optics mounting plates available for a wide range of popular optics.