| Image Thumbs | |
| Cert Num | 1305431 |
| Cert Date | 2015-08-28 |
| Catalog Number | C23a |
| Country | USA |
| Year | 1938 |
| Denom | 6c |
| Color | Dark blue & carmine |
| Grade | Ungraded |
| Description | Used |
| Opinion | it is a genuine usage of a vertical pair, imperf horizontal tied on second day of issue National Air Mail Week cover, the cover with a vertical file crease at the left. |
| Cert Link | http://psestamp.com/Cert/1305431 |