Refers to gold, silver, copper, iron and tin, and hardware is the mother of industry; The products of national defense foundation-hardware materials are usually divided into two categories: big hardware and small hardware. Big hardware refers to steel plate, steel bar, flat iron, universal angle steel, channel steel, I-beam and all kinds of steel products, while small hardware refers to building hardware, iron sheet, locking nails, iron wire, wire mesh, wire scissors, household hardware, various tools and so on. As far as the nature and use of hardware are concerned, it should be divided into eight categories: iron and steel materials, non-ferrous metal materials, mechanical parts, transmission equipment, auxiliary tools, working tools, building hardware and household hardware.