CPV code 51221000 designates Installation services of automatic airport check-in devices in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
51221000 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 51220000 (Installation services of checking equipment).