For maximum strength, the Shadow Systems multi-optic system incorporates a high strength polymer compression spacer to the chosen optic. This spacer is not required to keep the optic affixed to the slide. However, it does add rigidity to the system and offers a buffering effect in extreme use/hard use environments. However, they may accommodate other brands which have a similar outer footprint. This kit is designed to properly install your EPS, EPS Carry, or the Holosun K Optic to any MR/DR/XR firearm with the Shadow Systems standard optic cut. The "saddle" style configuration creates a properly tensioned zero-fit on one side and fills the space on the opposite side to create a sleek, cosmetically pleasing appearance. IncludesEPS Spacer Two Optic Mounting Screws