CPV code 43121000 designates Well-drilling machinery in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
43121000 sits under 43120000 (Coal or rock cutters and tunnelling machinery, and boring or sinking machinery) and groups 6 more specific sub-codes. When classifying a tender, choose the narrowest code that still covers the full subject of the contract.