CPV code 16520000 designates Unloading trailers for agriculture in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
16520000 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 16500000 (Self-loading or unloading trailers and semi-trailers for agriculture).