... Carbon steel,Stainless steel Specification of our nut: 1.NameDIN557 Square Nuts 2.StandardDIN, IFI, ISO, JIS, AS,BS, EN ... ., Black Oxided, Dacromet,Geomet,etc8.Production TechniqueCold forming,Hot forging,Machining,Heat treatment,etc9.Production Capacity2-3X20'GP ... Black Oxided, Dacromet,Geomet,etc8.Production TechniqueCold forming,Hot forging,Machining,Heat treatment,etc9.Production Capacity2-3x20'GP ...