No clue, the black lugs I bought back when I had the space grey watch came with the screwdriver and it also worked on the original classic buckle band.
I just took one apart this week for fun, haha. I had a pentalobe screwdriver from my iPhone and it took the screws out just fine, so I'd say find one of those.
Be aware, it's really easy to strip these screws, so just take your time.