1.spring steel made 2. square nut Cage NutCage nut made of spring steel, finish by galvanized. Cage material: By 65Mn ( spring steel )Square nut material: By steel or stainless steel Size: M4, M5, M6, M8, M10, M12Inch size is also available cage nut m4,m5,m6,m8,m10,m12/fastener cage nut/metal cage nut/square cage nut