Additional Lens Cartridges allow for optimal reticles and aiming solutions to be available at a moments notice Optically centered aiming points mean every Cartridge will have the same center and point of impact in the target Lens Cartridge accepts: 1 3/8" size lenses (sold separately) Includes: Cartridge (target facing) Single Up-Pin (.019" or .010") Two black retaining gaskets One White retaining gasket