This Order applies a tariff concession (item 50, Part III, Schedule 4 of the Customs Tariff Act 1995) to imported whipstock sub‑assemblies for oil and gas wellbore deviation systems (tariff heading 8431.43.00), effective 18 March 2009 until revoked. It mainly affects importers of those parts by lowering their customs duty while the concession is in force; the customs delegate implements and can revoke the concession under the Customs Act, so importers must ensure correct classification and supporting documentation.