Rob Roberts Gun Works RR1 Raptor Crio Plus 12 Gauge 17-4 PH Stainless Ste. 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. Specifications for Rob Roberts Gun Works 200274 RR1 Raptor Crio Plus 12 Gauge 17-4 PH Stainless Ste: Manufacturer: Rob Roberts Gun Works Fabric/Material: 17-4 PH Stainless Steel Gauge: 12 Choke Tube System: Benelli Crio Plus Rob Roberts Gun Works 200274 RR1 Raptor Crio Plus 12 Gauge 17-4 PH Stainless Ste