... steel;2.Surface treament: polished,galvanized,hot dipped,nickel plating;3.Stainless Steel 304 or 316 spring nut;(Size: 1/4",3/8 ... ",5/16",1/2",M6,M8,M10 ... ,M12);4.Competitive price and good quality;5 ... Certified galvanized spring nut(M6,M8,M10,M12,1/4",3/8",1/2",5/16")