It Sein is een straat te Sint Nicolaasga in de gemeente De Fryske Marren en is gelegen in de Nederlandse provincie Friesland.
| Postcode | Huisnummers |
|---|---|
| 8521 DM | 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51; |
| 8521 DN | 2, 4, 6, 8, 10, 12, 14a, 14, 16a, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50; |