Made from 17-4 heat treated stainless steel, these chokes are for Browning Invector Plus (BIP) shotguns. 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 Larger than #4 may be used in our Turkey Choke Tubes. These choke tubes are backed by Carlson's Lifetime Warranty and Made in the USA!