I'm wondering why this machine came with two buttonholers? Both the newer beige one and the older (original) black one will fit your featherweight. Buttonholers usually came with five standard buttonhole cams and you could buy a set of additional sizes but 23 cams are more than enough for the two you have, so you must have some duplicates. Not every Featherweight comes with a Zigzagger so this is a bonus.