The Nautilus collection was introduced in 1976. Patek Philippe was looking for a strong design and an inimitable personality. An inspiration for its design soon emerged: The universal shape of a porthole found on virtually all maritime vessels. Product Details: Mechanical self-winding movement, Caliber 240 PS IRM C LU, Moon phases, date by hand and power reserve indicator. Seconds subdial, Black-blue dial, gold applied hour markers with luminescent coating. Sapphire-crystal case back. Water resistant: 60 m Case diameter (10-4 o'clock): 40 mm