A paragon of robustness, reliability and elegance, the Oyster case of the Cosmograph Daytona and GMT‑Master II – both 40 mm in diameter – as well as that of the Sky‑Dweller – 42 mm – is guaranteed waterproof to a depth of 100 metres (330 feet). The middle case of the versions presented is crafted from a solid block of 18 ct yellow or Everose gold. Both the Triplock winding crown, fitted with a triple waterproofness system and protected by an integral crown guard, and the Twinlock winding crown, with a double waterproofness system, screw down securely against the case, as do the chronograph pushers on the Cosmograph Daytona. The crystal – featuring a Cyclops lens at 3 o’clock for enhanced legibility on models with the date function – is made of virtually scratchproof sapphire and benefits from an anti-reflective coating.