Tariff Concession Order 1009585 applies item 50 in Part III of Schedule 4 of the Customs Tariff Act 1995 to skid‑mounted hydrogen and oxygen gas generators (tariff classification 8405.10.00), effective 23 February 2010 and continuing until revoked under the Customs Act. Mechanically, it changes the tariff/duty treatment on import: importers of these generators must use the stated classification and may claim the Schedule 4 concession; the concession is administered by the customs delegate and can be revoked under ss 269SC–269SD.