High-voltage test instruments, electric heating appliances, cable trays, safety conductors, electrical equipment, nano energy-saving heaters, photon far-infrared heaters, energy-saving and environmental protection equipment, nano thermal insulation clothing processing and sales; sales of insulation materials, environmentally friendly dust bags and accessories, metallurgical accessories, metallurgical materials, dust collectors and accessories, polyimide films, ferrosilicon, silicon manganese, and ferroalloys.