It's a technical watch, first released in 1972 and meant to be a "tool watch" through and through. In the 1970s Zenith catalogs, it was sold as a "Pilot Divers" watch, which if you know link the history of watchmaking, link you might be thinking doesn't make much sense. There's a link longstanding superstition that pilot's watches shouldn't be waterproof because they'll then somehow attract water. I imagine when you're flying high above the clouds, you'd rather stay up there and not in the water. link