I found this information: class 66 Metal Bobbins for Singer Models: 66, 99, 101, 185, 192, 201, 247, 288, 327, 328, 329,401, 403, 404, 413, 416, 418, 466,,476, 477, 478, 513,514, 518, 522, 527, 533, 534, 538, 560, 714, 717, 719,734, 774, 776, 814, 834, 4610, 6212, 6214, 6215, 6217,6233, 6100, 6700, 7100, 8100 and other drop in bobbin machines.