Made from 17-4 heat treated stainless steel these chokes are for the Benelli Crio/Crio Plus system. - Steel Lead & Hevi-Shot may be used in all constrictions with the exceptions listed below. - No Steel shot larger than #BB or speeds exceeding 1550 fps should be used in choke tubes tighter than full. - No steel shot allowed in our turkey constrictions - These choke tubes are backed by Carlson's Lifetime Warranty and Made in the USA!