Design, research and development, and sales of precision electronic components; Domestic trade. Sales of mechanical and electrical equipment; Sales of distribution switch control equipment; Research and development of distribution switch control equipment; Sales of electronic components and electromechanical equipment; Sales of metal cutting and welding equipment; Sales of optical instruments. Except for projects that require approval according to law, business activities can be carried out independently based on the business license. The licensed business projects are: Import and export of goods; Technology import and export. (For projects that require approval by law, business activities can only be carried out after approval by relevant departments. The specific business projects shall be subject to the approval documents or licenses issued by the relevant departments. )