The Longines Master Collection Retrograde Moonphase L2.738.4.71.6 is a 41mm stainless steel watch featuring a silver 'barleycorn' dial with painted Roman numerals and blued steel hands. It is powered by the automatic Calibre L707 movement, operating at 28,800 vibrations per hour with a 48-hour power reserve. The watch offers retrograde displays for day, date, small seconds, and a 24-hour second time zone, along with a moonphase display at 6 o'clock and a day/night indicator at 12 o'clock. The case has a thickness of 16.4mm and is water-resistant up to 30 meters. It comes with a stainless steel bracelet equipped with a triple safety folding clasp and push-piece opening mechanism. Reference number: L2.738.4.71.6.