. Designed especially for vintage sewing machines and modern spools of thread, the Thread Post converts your vertical spool pin into a horizontal thread delivery system. No more twisting and resisting! From spool to needle, thread will flow smoothly and evenly, providing better stitch formation. Thread Post fits perfectly atop the Singer Featherweight 221, 222 plus any vintage Singer with a vertical spool pin on top of the machine (e.g. Singer 15, 66, 99, 127, 128, 185, 192 Spartan, 201, 237, 327, 328, 401, 403, 404, 500, and 503 - use far right pin on Slant-O-Matic & Rocketeer models)