This LeCoultre Master Mariner HPG 9511 dual-calendar vintage watch features a 14K Gold Electroplate. Even after decades of wear, the plating remains a genuine 14K gold alloy (containing 58.3% pure gold). It's achieved by depositing real 14K gold onto the case through a chemical electrolysis process. Cal. 164 (HPG 36000) Movement: In the early 1970s, the traditional Swiss watchmaking industry faced a significant challenge from Japanese quartz watches. To counter the extremely high accuracy of quartz watches and reduce development costs, top brands such as Jaeger-LeCoultre, Girard-Perregaux, Doxa, and Zodiac engaged in rare technical collaborations. Based on the high-quality plate circuitry of the renowned manufacturer A. Schild, they jointly developed and launched this ultra-high frequency (Hi-Beat) movement. Jaeger-LeCoultre designates it as Cal. 164 (Cal. 165 for the single-date version), while Zodiac names it the famous Cal. 72 / SST 36000 series movement. 【Brand】LeCoultre 【Model】LE C 9511 【Movement】Original Caliber 164 automatic movement 【Crown】Replacement crown 【Case Diameter】37*37mm (excluding crown) 【Dial】Original dial 【Strap】Replacement strap/clasp (aftermarket) 【Condition】Timekeeping and functions are normal; serviced and oiled in November 2015 【Functions】Manual + Automatic. Date quick-set, day of the week without quick-set.