In the 1930's, Panerai created watches for the Italian Navy. Panerai Radiomir Black Seal Replica watches were made of authentic stainless steel, which was resistant to extreme environmental conditions. This durable steel is a key part to the design of each Panerai watch. The 45mm steel case guarantees that the Panerai Black Seal replica is water-resistant to a depth of 100 meters. The watch is constructed from AISI 316L steel, which is resistant to both shock and the elements. It is also resistant to corrosion and is hypoallergenic. The movements inside of the Panerai Black Seal replica have an XI caliber and are made to withstand temperatures between -10 degrees Celsius and +60 degrees Celsius.