Rolex Datejust 31 mm

Rolex Datejust 31 mm, reference 278240-0010, has a 31 mm steel case with a domed bezel. The case measures 31 mm across and pairs a screw-down crown with a scratch-resistant sapphire crystal fitted with a Cyclops lens over the date. Inside is the calibre 2236, a self-winding Manufacture movement with a power reserve of about 55 hours, certified as a chronometer. The dark grey dial carries luminous hands and indices, along with a central seconds display and date function. Rolex fits this reference with a steel bracelet closed by a concealed folding Crownclasp. The screw-down crown, part of the Twinlock system, helps hold the case to its 100 metre water resistance rating.