[1] Product type: High quality marine grade canvas and upholstery boat cover snap button fastener kit[2] Meterial: Snaps are made of brass and nickel-plated for added durability. The screws are made of 304 stainless steel, which offers good corrosion resistance in bad environment like high temperature, cold weather, and high humidity areas. They have superior rust resistance and the excellent of oxidation resistance, which can ensure long time using and prolong screws lifespan