CPV code 73410000 designates Military research and technology in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
73410000 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 73400000 (Research and Development services on security and defence materials).