Introducing Carlson's revolutionary Bismuth bone buster Choke Tubes, painstakingly crafted to produce outstanding, tightly concentrated patterns when used with any Bismuth ammunition. Engineered with meticulous precision using 17-4 heat treated stainless steel, these tubes feature an elongated parallel section within the Choke, surpassing the capabilities of standard factory variants. Subjected to rigorous testing with a diverse range of loads, these chokes emerge as the ultimate selection for achieving devastating Bismuth patterns. You can choose between the mid range (with a .025 constriction) or the extended range (with a .045 constriction), both of which seamlessly accommodate lead and Hevi-Shot loads. The mid range variant complements all steel shot types, while the extended range version can handle steel shot up to #2 size. Enhance your shooting experience with these state of the art Bismuth Choke Tubes, and enjoy peace of mind with Carlson's comprehensive lifetime Warranty.