These are replacement plastic spool pins for a Singer 401.
The photos show two pins so you can see where they go for comparability, however, this item is for only one pin. A quantity of 1 = only (1) pin.
This pin is suitable for the following Singer models: 327, 328, 329, 337, 338, 347, 348, 401, 403, 404, 413K, 413K13, 416K, 418, 457, 466, 476, 477, 478, 502, 507, 509, 513, 514, 518, 522, 527, 533, 534, 538, 6513 - 6548