The rr3 choke is made for long-range targets.This choke is specifically designed for geese and open water ducks.The internal cuts provide optimal pattern density when paired with the correct loads.These choke tubes are built from years of product development and innovations using the highest advanced technology available.They are made out of 17-4 ph u.S.Stainless steel.*over-shotguns can have a rraptor choke in only one barrel.The design of the choke does not allow for placement in both barrels*Gauge: 20 GaugeMaterial: 17-4 PH Stainless Steel