This type of screwdriver is the kind that was originally included with the Singer Hemstitcher & Picot Attachment and is therefore difficult to find today. It was often misplaced from the original box or tossed in a drawer or sewing basket. A very handy tool to have because it makes loosening and tightening the throat plate screws much easier. However, this can be used for many other hard to reach areas as well and is a good screwdriver to have in your Attachments Box, especially if you are akin to servicing your own machine and need to remove your throat plate at any time.
The throat plate screws only need to be finger tight. So, just because you have the right tool does not mean they need to be lug-nut tight!
If you would like more information about the Singer Hemstitcher & Picoting Attachment, click here.