precision patterns Guaranteed. Carlson's proudly presents the innovative Bismuth bone buster Choke Tubes, expertly designed to achieve exceptional, concentrated patterns when using Bismuth ammunition. Crafted with precision through CNC machining from 17-4 heat treated stainless steel, these tubes feature an extended parallel section within the Choke, surpassing traditional factory chokes in performance. Rigorously tested with a variety of loads, these chokes offer the ultimate solution for producing devastatingly potent patterns with Bismuth. You can choose from both mid range (with .025 constriction) and extended range (boasting .035 constriction) options, and these Bismuth chokes are compatible with lead and Hevi-Shot loads. The mid range variant is suitable for all steel shots, while the extended range version caters to steel shots up to #2 size. Step into the world of bone crushing, concentrated patterns with Carlson's all-new Bismuth Choke Tubes. Rest assured in the quality of these chokes, backed by Carlson's lifetime warranty for your peace of mind.