Grand Seikoさんのインスタグラム写真 - (Grand SeikoInstagram)「The 25th anniversary of the 9S mechanical calibers 25 years of innovation and evolution Chapter 17: Precision in every aspect of time Caliber 9SA5 is Grand Seiko’s most precise mechanical movement in more ways than one. Thanks to its 36,000 vibrations per hour, its Dual Impulse Escapement and its Free-sprung Balance, it keeps time with a precision rate of +5 to -3 seconds a day, but its accuracy extends also to the way the date is presented. In most watches, the date takes several hours to change but Caliber 9SA5 has a special mechanism that ensures that it changes within the blink of any eye. At the heart of this mechanism is a date indicator drive wheel that is just seven millimeters in diameter. Its springs and movable date finger, all made with MEMS technology, ensure that the date changes instantaneously. Even though it is hidden from view, this date-change mechanism is beautifully finished by Grand Seiko’s craftsmen and women for whom precision and craftsmanship are matters of equal pride whatever the component, visible or not. To watch the date change in a Caliber 9SA5 watch is to appreciate the value of their skill. #grandseiko #9Smechanical」7月18日 12時00分