The Panerai Luminor case came into being as a result of the need to make the Radiomir (Panerai's first case) more water-resistant. To ths end, the bridge device with clamping lever was added, protecting the winding crown and making it more water-resistant, while the large straight lugs, milled with the case from a single block of metal, replaced the wire strap attachments, welded in place. For the first time, a new Panerai model uses a unique case which marks the historic development of the Radiomir case, the Luminor 1950 3 Days - 47mm. The Luminor 1950 of the new model, executed in polished steel in the classic size of 47mm, has a rounded, cusp-shaped caseband, directly descended from the cusion design of the case which still today is the characteristic of Radiomir watches.