Audemars Piguet. A stainless steel automatic calendar chronograph wristwatch Royal Oak Offshore, Ref 26170ST, No.9739, Purchased 20th December 2013Audemars Piguet. A stainless steel automatic calendar chronograph wristwatchModel: Royal Oak OffshoreReference: 26170ST, No.9739Date: Purchased 20th December 2013Movement: Jewelled automaticDial: White grid, blue Arabic numeral hour markers, raised outer tachymetre scale, subsidiary dials at 12, 3 and 6 for seconds, 30 minute and 12 hour recording, date aperture at 3, polished baton hands with blue inserts, centre chronograph handCase: Brushed and polished tonneau form, back secured by 8 screws, 8 screws to bezel, screw down crown flanked by twin chronograph buttons, No.F62202Strap/Bracelet: Black Audemars Piguet rubberBuckle/Clasp: Signed folding claspSigned: Case, dial & movementSize: 46mm Accompaniments: Audemars Piguet box, outer card (AF), Warranty and Authentication Certificate, Instructions for useThe Audemars Piguet Royal Oak series is regarded by many as the quintessential sports watch. The iconic design revered by horological connoisseurs is instantly recognizable with its structured strongbox case with structurally integral octagonal bezel secured by eight hexagonal screws. In 1993, Audemars Piguet took the next step in the evolution of the Royal Oak with the introduction of the Royal Oak Offshore. The first Offshore reference was the 25721ST and the larger dimensions of the watch earned it the nickname 'The Beast'. Over the years Audemars Piguet have released numerous modifications to the model whilst maintaining the key elements conceived first in the 70s by Genta and then in the 90s by Emmanuel Gueit.