Singer Class 66 Metal Bobbins for use on Singer sewing machines models 66, 99, 101, 185, 192, 201, 247, 288, 327, 328, 329, 401, 403, 404, 413, 416, 418, 457, 476, 477, 478, 500, 717, 719, 814, 834, and series 6100, 6500 and 7100. Can also be used in other drop-in bobbin machines. Each package contains (4) high quality metal bobbins.