For maximum strength, our multi-optic system incorporates a high strength polymer compression spacer either in front of or behind 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. The spacers are sized specifically for certain, commonly selected optics. However, they may accommodate other brands which have a similar outer footprint.
The included spacers are designed specifically to fit the Trijicon RMR, Holosun with RMR-style footprint, Leupold DeltaPoint Pro, and Vortex Viper. Depending on the outer footprint of your chosen optic, the spacers may accommodate other optics as well. Check fit to determine if they will work for your optic if it is different from those listed above. You may also, in cases where a spacer is too large for the optic you have chosen, carefully modify the spacer with sandpaper to fit your optic.