Ultimate Arms Gear Mossberg 500-590-835 Tactical Package: Includes New Generation CQB 4 Reticle Dual Red / Green Open Reflex Sight with Weaver-Picatinny Rail Mount, Ultimate Arms Gear Weaver-Picatinny Aluminum Rail Base Mount, Lithium Battery and a Lens Cleaning Kit Tubeless Open Reflex Design 4 Separate Reticle Patterns In Both Red and Green 6 Diferent Brightness Settings (3-Red 3-Green) Weaver-Picatinny Rail Base Windage and elevation adjustments