The  Panerai Radiomir plays an important part in the history of the brand. Nominally, French patent records dating all the way from 1916 show a filing bearing the name Radiomir for a particular Radium-based luminous powder developed by the replica watch company to satisfy the requests of the Royal Italian Navy. Panerai replica had already been providing instruments to the navy for years prior, and this patent was another step forward in their budding friendship. 
Almost 20 years later, the Radiomir as we know it was born. Built for the Frogmen—a particular commando division of the Royal Italian Navy—the Radiomir was a big 47mm steel cushion-cased wristwatch with wire lugs welded to the case. These pieces by the  Panerai were designed with bright luminous indices in a “California dial” configuration, straps long enough to wrap over a diving as well as the waterproof cases. Some of the early variants of these fake watches that have surfaced over the years have been found fitted with hand-winding Rolex calibers.
Not only was this of great help to the members of the Navy who put them to the test in the field, but also created a special aesthetic that makes a fake Panerai watch easy to distinguish from anything else on the marketplace. Though minor design tweaks have been made along the way, this overall aesthetic has remained a vital part of the Panerai lineup, and the brand has unveiled a significant range of Radiomir models through the years.
The Panerai Radiomir 42mm was first unveiled in 2010, and received a very warm welcome from replica watches enthusiasts all around the world. While the huge majority of the replica Panerai‘s offerings were generally on the larger side at the time, the new Radiomir was the first in this design to be scaled down to a more modest 42mm. Owing to its flat construction and wire lugs, it still has ample presence on the wrist, though this update surely opened up the doors to more collectors that previously found the model a touch too oversized. Even though a rather casual-looking piece overall, it obviously has the right profile to tuck under a shirt cuff while named in for day-to-day office duty.