Zaffiri Precision Stainless Steel Slides are designed with tight tolerances to increase accuracy and performance. There are two different optic configurations, as well as and variety of coatings for a customized look. These are among the best aftermarket slides available for Springfield Armory. The Shield RMSc, Holosun 407k/507k, and Sig RomeoZero optic cuts are all the same footprint with NO rear lugs and slightly lowered front lugs. This makes the same footprint compatible with all 3 companies. Optic Cover Plate is included! The screws are all slightly different for optic mounting. Optic mounting position in front of the factory location of the rear iron sight. Screws are 6-32 thread. Blue Loctite recommended for proper sight retention.