This low-profile hex nut meets ISO 4035 standards and is made of steel with a Zinc Flake coating (ISO 10683 flZnnc 04), Cr(VI+)-free. Rated at strength class 040, it's a thin jam nut with reduced load capacity, designed to keep other nuts from vibrating loose. The zinc-aluminum surface treatment delivers greater corrosion resistance than a pure zinc coating of the same thickness, with no risk of hydrogen embrittlement. The nut features metric threading.