Dug out some of my Singer needle packets to look at them. I think I've got them in age order - going by the emblem changes.
The oldest does not have the 15x1 on it - just the Singer machines it fits. I know Singer started using teh Green manuals around 1913, and the 127 came out about the same time.
The next one has a size, but the emblem is the same (lady with full dress working a treadle machine). The third shows the woman in a short dress at an electric machine - which changed around 1929.
The next has the same logo, though updated a bit, and Made in USA added. the fifth has the logo updated in 1947, with the asterisks that was added in 1948 that was used for the green manuals until they were discontuned in the mid 50's
the sixth is a later design,
Thelast three are even newer - interestingly - the first of this group has 15x1 and then (2020) and the next newer has 2020 (15x1) on it - also note the name change from Singer Mfg Co. to Singer Company.
