In the 60s/70s:National Geographic had a culture-of-the-month club where kids got mail packages. What was it?

When I was young I used to get really cool international stuff in the mail every month because of this club. I got a pan-flute from Africa and a ball-and-cup game from Mexico... Does anyone remember the details? A web search of "explorers club" doesn't seem to return the right results... Perhaps someone with really old issues can find a reference in late 60s or early 70s issues of National Geographic.