Packing group varies (II/III) by concentration or form per the §172.101 row — verify against the current edition for your material.
This is the reference entry for UN1999.
To verify your actual package — labels, marks, SDS and packaging — scan it with DG Inspector. It reads the real evidence in front of you and shows the reasoning so you can check it.
A reference lookup is a dictionary, not a compliance verdict. It tells you what UN1999 requires; it cannot confirm that your specific shipment meets those requirements.