... .Material: SS304 or SS316;carbon steel 2.Surface:polished;galvanized 3.Good price and quality Detailed Product DescriptionMetal stamping part/Fastener ... Steel 304 or 316 spring nut;(Size: 1/4",3/8",5/16",1/2",M6,M8,M10,M12);4.Competitive ... Certified galvanized spring nut(M6,M8,M10,M12,1/4",3/8",1/2",5/16")