Since I love playing with my attachments - I pulled some of my Greist buttonholers out.
Here are the Red New Home and the Green National boxes - these are both "fuzzy" boxes.
I also pulled out the White -
here are the business ends, White, Free/New Home and National. This is what you really need to look for. BTW - the majority of the Greist Buttonholers you'll find are SIDE CLAMP, and that is different than theses three.
And the national on my Two Spool - fits just fine.
For fun I took off the foot clamp and put the White on - first problem, with the foot lowered, it didn't actually come down far enough, and the needle and guide didn't line up correctly either.