To achieve an extended power reserve Panerai introduced an innovative power train based on three barrels in series to provide excellent time-measuring performance throughout the whole period of the power reserve. By means of this system, the force of the spring remains almost constant for the whole duration of the winding, so as to optimise the movements accuracy and to reduce the wear of the components to a minimum. AISI 316L 1.4435 stainless steel is Officine Panerais material par excellence since it is highly resistant to corrosion and is hypoallergenic, making it ideal for contact with the skin. The Panerai watches created for the Italian Navy were made of austenitic stainless steel, a reliable material that was also resistant to the extreme environmental conditions in which the commandos operated.