The Rob Roberts Final Strut Optima 12 Gauge choke is an expertly crafted accessory designed for optimal performance. With a constriction diameter of .655 this choke is ideal for those who seek precision and reliability in their shooting experience. Crafted from 174 PH U.S. Stainless Steel it reflects years of innovative development and advanced technology. Specifically optimized for use with bismuth shot it is a perfect match for the RRaptor BIZ choke. This choke is a valuable addition to the RRaptor Series offering superior performance in a robust and durable design. Note that it is designed for single-barrel use enhancing its specialized functionality.