The Mesa Tactical reflex SureShell carriers for Benelli M4 feature an integrated optics mount with the Aimpoint ACRO footprint. In place of traditional Picatinny rail, the reflex SureShell carriers ACRO footprint is low enough that there is an absolute co-witness between the optic and the factory ghost rings. Shells can be loaded from the top or the bottom. FeaturesIntegrated optics mount with Aimpoint ACRO(R) footprintAbsolute co-witness with factory ghost ring sightsRubber retention system solidly holds shells in place loaded from top or bottomMounts via drilled and tapped receiver holes Note: ACRO Sight is not included Fits Red Dot Sights with Aimpoint ACRO footprint (Not all inclusive)Aimpoint ACRO P-1/P2Aimpoint ACRO C-1/C2Steiner MPSBurris FastFire EGriffin Armament Griffin Micro SightC&H DutyC&H Duty-XLVector Optics Enclosed Frenzy Plus