Sales of hardware products, hardware tools, Wujiaodian, wire processing equipment, mechanical and electrical products, distribution cabinets, control cabinets, cables and wires, low-voltage complete sets of equipment, workbench assembly lines, assembly and test fixtures, demonstration display boxes, and non-standard automation equipment; technical development of mechanical and electrical products and door-to-door installation and maintenance services; HVAC pipeline engineering design and installation; strength and weakness