These wrenches are made of 301 full hard stainless steel AMS5519. And fit #4, #6, #8, AN3 (#10), AN4 (1/4″), AN5 (5/16″), AN6 (3/8″), AN7 (7/16″), AN8 (1/2″) washers. They will not rust and will always maintain their rigidity and tension. Each wrench is precision cut so the washers snap into position and held firmly. The Washer Wrench is 0.042 thick which is less than most washers. This allows for easy insertion without obstruction. These wrenches fit AN960, NAS, and L washers. Each set of wrenches come in a convenient pouch to help with organizing. Complete set consists of 4 wrenches with 8 different sizes.