Carlsons Benelli Crio/Crio Plus 12ga Flush Full Chokes are made from 17-4 heat treated stainless steel, these chokes are for the benelli crio plus system. steel or lead shot may be used in these choke tubes. steel shot larger than bb or speeds faster than 1550fps should not be used in any choke tighter than full. Fits all 12ga Benelli Crio/Crio Plus choke systems Manufactured from 17-4 Heat Treated Stainless Steel Can be used with Steel, Lead, Hevi-Shot, or Bismuth ammo Lifetime Warranty