I would say check the NPA site, but I see you've gotten things worked out.
They don't list them, lol. But I have a copy of their SOP and it said size 7 in there, which is why I was confused about the breeder saying 9. And then the birds he sent me...are wearing size 7. Lol.
When I saw the NPA site recommending 9 for things like Modenas I was like, no way my guys are that big.