Design, technology development, technology transfer, and technical services for energy-saving and environmental protection complete sets of technologies and equipment; Sales of electronic products, communication equipment, construction materials, hardware and electrical appliances (excluding electric bicycles), mechanical equipment (excluding passenger cars), chemical products (excluding hazardous chemicals and Category I precursor chemicals), computer software and auxiliary equipment; Specialized contracting; General contracting. (Market entities are entitled to independently select business items and carry out business activities in accordance with the law. For items subject to approval according to the law, business activities shall be carried out within the scope approved by the relevant authorities. It is prohibited to engage in activities that are prohibited or restricted by national or Beijing municipal industrial policies