Silver-tone stainless steel case with silver-tone stainless steel oyster bracelet and fixed silver-tone stainless steel bezel. Black concentric dial features silver-tone hands and Arabic numeral hour markers. Analog dial with date display at the 3 o'clock position. Powered by Rolex Calibre 2235 automatic chronometer movement with 31 jewels, beating at 28800 vph, and offering a 48-hour power reserve. Scratch-resistant sapphire crystal. Screw-down crown. Solid case back. Round case size 31 mm. Fold over clasp with safety release. Water resistant to 100 meters / 330 feet. Functions include date, hour, minute, second, and chronometer. Datejust 31 Series. Swiss Made. Item Variations: 178240, 178240-BKCAO, Rolex-178240, Rolex-178240-BKCAO.