2 Singer Tension check springs.  Part# 66774 .  Genuine Singer Replacement Part . Best Spring you can buy. Will not Break or lose shape as easily as other cheaper springs being sold . 

Will Fit Singer Models

1021, 1022

1200, 1200-1, 1247, 1263, 1280, 1288

1730

1802, 1803, 1812, 1852, 1853, 1862, 1872, 1873

201, 201-2, 221 Featherweight, 222, 223, 237, 239, 240, 2404, 241, 242, 2430, 247, 247AP, 248, 250, 251, 252, 257, 258, 259, 2712, 2718, 2722, 2724, 2730, 2732, 288, 293B

301, 301A, 3101, 3102, 3103, 3105, 319, 327, 327K, 328, 329, 337, 338, 348, 353, 354, 360, 362, 366, 367

401, 401A, 403, 404, 413k, 416, 416k, 417, 418, 4522, 4525, 4526, 4528, 4530, 4538, 457, 466, 476 Stylist, 476K Stylist, 477, 478, 4825, 4828, 4830

500, 502, 503, 507, 509, 513, 514, 518, 522, 527, 533, 534, 538, 543, 560

600, 600E, 6011, 6012, 6021, 603, 604, 6102, 6104, 6105, 6106, 6110, 6120, 6130, 6136, 6146, 6152, 6156, 6174, 6184, 620, 6201, 620E31, 6202, 6211, 6212, 6214, 6215, 6217, 6221, 625, 625E1, 625E6, 625E7, 626, 628, 629, 630, 630E,635, 635E3, 635E6, 635E7, 636, 638, 639, 640E, 645, 646, 648, 649, 6513, 6522, 6528, 6533, 6543, 6544, 6548, 6606

7015, 7021, 7025, 7101, 7102, 7104, 7105, 7106, 7108, 7110, 7136, 7174, 7184

8002, 8007, 8019, 8100, 8200, 8500, 8502, 8505, 8518, 8600, 8602, 8605, 8606, 8610, 8614, 8618, 8774

9500, 9600, 9900

CE-350 Futura III, DL17