The Rolex-made 3646 was released around WWII (1940 to 1944) to Italian Navy divers. These Italian frogmen were famously successful. Not to be outdone, the German Navy adopted Panerai a few years later in the famous Kampfschwimmer. The 3646 was the first to feature what has become known as the radiomir dial, a 3-6-9-12 layout. Radiomir was a trademarked name for the glowing dial lume, a first of its kind and very useful for divers. It turned out to , but that’s another matter. The success of this brilliant 3646 design is Panerai’s foundation today.