I just got these today - These are what all the Manual drawings show - the one with the pin. Don't know when Singer switched to the style without the pin- probably found out it wasn't needed so they stopped putting it in.
This is one of my favorite - came with the British set of early attachments
These all have the same part number - the two bright ones also have "Singer USA" on them.
Some of my others - I've tossed them in the box as I get them, and have not yet gone through to see what I need for all my sets (and I have a lot of sets). All of these came with sewing machines and/or attachments.
