The Flown STS-8 Cover is unique, as it was the first to record the flight into space with originating and returning postal cancellations. 500,000 covers were produced. Only 261,900 covers were actually flown. 2,523 covers were damaged during the flight and the remaining unflown covers were destroyed. Presently, 259,377 flown covers exist.
The Space Store was able to recently acquire 8 of these.