The Carlsons Bismuth BB 12 Extended Range Brown Invector is a precision-engineered choke tube designed to deliver exceptional performance with bismuth ammunition. Crafted from durable 17-4 heat-treated stainless steel it features a longer parallel section inside the choke for improved pattern density compared to conventional factory choke tubes. This choke tube has been rigorously tested with various loads to ensure devastatingly accurate patterns. It is compatible with all lead and Hevi-Shot loads as well as steel shot no larger than #2. Perfect for 12-gauge firearms this choke offers unmatched reliability and performance for hunters and shooting enthusiasts alike.