If you want the ultimate long range waterfowl choke, then this choke is for you. It can deliver 90% to 100% shot patterns round after round. Shoot thousands of rounds of large steel shot without fear of choke expansion. The Super Waterfowl choke has been thoroughly tested with almost every load of steel, Tungsten Matrix, Tungsten Polymer and Hevi-Shot (Tungsten Nickel) in 2 3/4, 3 and 3 1/2 inch shells, with sizes of # 6-5-4-3-2-1-BB-BBB-T-TT-TTT. Made from special space age alloy that has a strength level of approximately twice that of 17-4. A unique alloy capable of withstanding high pressure and stress.