The new Nautilus Ref. 5711/1 in steel, has a case diameter of 43mm, one millimeter larger than its 1976 predecessor. This slight increase is due to the rounder contours of the lateral hinge ridges. The new three-part case has a screwed back with a sapphire-crystal case back and a screw-down crown. It is water resistant to a depth of 120 meters. The movement is the self-winding Patek Philippe calibre 315 SC, powered by an extra-heavy 21K gold central rotor. The dial displays the hours, minutes, sweep seconds, and the date in an aperture at 3 o'clock.

Mechanical self-winding movement with date
Caliber 324 S C
Center sweep second hand
Black-blue dial, gold applied hour markers with luminescent coating  
Screw-down crown
Sapphire crystal case back
Water resistant to 120 m
Case diameter (10-4 o’clock): 40 mm