Pack of 3, Thread Tension Check Springs For Singer Sewing Machine. Part # 66774. These high quality tension check springs will fit following Singer machines : 201, 201-2, 221 Featherweight, 222, 223, 237, 239, 240, 241, 242, 247, 247AP, 248, 250, 251, 252, 257, 258, 259, 288, 293B, 301, 337, 338, 348, 401, 416, 500, 502, 503, 507, 509, 513, 514, 518, 522, 527, 533, 534, 538, 543, 600, 603, 604, 620, 620E31, 625, 626, 628, 629, 630, 630E, 635, 636, 638, 639, 640E, 645, 646, 649, 1200-1, 1247, 1280, 1288, 1802, 1803, 1812, 1852, 1862, 1872, 1873, 2404, 2430, 2732, 3101, 3102, 3103, 3105, 4522, 4525, 4526, 4528, 4530, 4538, 4825, 4828, 4830, 6011, 6012, 6021, 6102, 6104, 6105, 6106, 6110, 6120, 6130, 6136, 6146, 6152, 6156, 6174, 6184, 6201, 6202, 6211, 6212, 6214, 6215, 6217, 6221, 6513, 6522, 6528, 6533, 6543, 6544, 6548, 6606, 7025, 7101, 8019, 8502, 8505, 8518, 8602, 8605, 8606, 8610, 8614, 8618, 9900