The nuts are made of high quality carbon steel. Nickel-plated surface for good resistance to rust and oxidation Kit consists of 50pcs nuts, threads for your choice: EU20-M5, EU30-M5, EU30-M6, conforming to European standard Easy to use and convenient to connect aluminum profiles to other parts Suitable for European standard aluminum extrusion profiles: EU20 is used on profiles with 6mm slot, while EU30 is used on profiles with 8mm slot