Patternmaster extended chokes are designed to be used with the 3 1/2″ shells for maximum pattern and density. The difference between the Patternmaster Extended chokes and Patternmaster Standard/Long Range is the length the tube sticks out the barrel. Patternmaster concept is that the “studs” inside the choke grabs the base of the wad as it passes through while the front of the wad is flush with the front of the tube. Since the wad is longer in the 3 1/2″ shells we have made the tube longer to maintain a tight, dense pattern. This tube can be used with 3″ or 2 3/4″ shells also for a tight dense pattern. Patternmaster’s 12ga Benelli Crio/Beretta Optima Plus will interchange with Benelli Super Black Eagle II, M2, Ultra Light, and Current Benelli Production Sport II, Super Sport, Cordoba, and Montefeltro; Beretta A391 Extrema II, Vinci, and Super Vinci; and Tri Star 3 ½ (current production); just to name a few. For more information about your shotgun interchange please see the firearm owner’s manual or contact the firearm manufacturer.