UNC Hexagon full nut 5/8 inch -11 A4 Stainless Steel A4 grade stainless steel has a greater corrosion resistance than A2 in certain environments. It is often used for Marine applications especially when coming into direct contact with salt water Dimensions: 5/8" x 11 TPI 28 mm Across the flats 23 mm Point to Point 13 mm thickness