Mustad Z-Steel 7691-ZS Southern and Tuna Hooks (Old Reference: 7691Z) feature Mustad’s Z-Steel finish, resulting in extreme corrosion resistance. Mustad’s new Z-Steel finish has proven to be the most corrosion-resistant hook finish on the market today—including stainless steel. Z-Steel is a unique alloy that is combined with hi-carbon steel to create hooks that are sharper, stronger and virtually indestructible in even the most demanding fishing conditions. Mustad Z-Steel 7691-ZS hooks feature a knife edge point.