I think the codes relate to the size of the heads and the type of set/packaging – plastic slip, hard case, solid base.
I bought the HS30080-P05 set which is sizes Ø0.50, Ø0.60, Ø0.80, Ø1.00 and Ø1.20mm.
https://www.ebay.co.uk/itm/263546041715
I already had a good quality 1.6mm and I've found I've only ever used that and the 1.2mm for bracelet links. I doubt a link screw would go smaller than a 1.2mm, but there are obviously other screws in the watch that will need smaller.
If it's just bracelet links then I reckon a 1.2mm and 1.6mm will be fine.