This is an original Singer part and not a reproduction - genuinely vintage! An uncommon little attachment foot that produces a very, very narrow hem - about 3/32 inch.
The fabric feeds from the front of the foot, while rolling and curving to form a very tiny hem. Lovely for doll dresses, hemming hankies or when using cotton voile, lawn or sheer fabrics. This attachment is not suitable for heavier weight fabrics.
Granted, if you are unfamiliar with this attachment, it takes a lot of practice and you will need to follow the directions carefully, slowly and precisely.
Instructions will be included with your attachment.
LOW SHANK (only): fits the Singer Featherweight 221, 222K and all low, vertical shank Sewing Machines (i.e. 15, 27, 28, 66, 99, 185, 127, 128, 192, 201, 206, 237, 306, 319, 320, 328, as well as many other brands besides Singer)