Robbins Medals have been produced for, and flown on, every manned U.S. mission since Apollo 7.
Between 255 and 450 Robbins medallions were minted for each Apollo mission. The medallions for the first few flights were struck with blank space on the reverse for the launch and return dates to be added post-flight. For the moon landing missions three blank fields were included for the launch, lunar landing, and return dates.
The fact that the Robbins medallions are flown, closely associated with the astronauts, and available to collectors in very restricted quantities makes them very sought-after collectibles.