Gustave Sandoz 18k Gold Pair Case Pivoted Detent Chronometer Pocket Watch. Gustave Ami Sandoz & Fils 18k Gold Pair case Pocket Chronometer with fascinating early stem-wind and pin set system. Chronometer balance with gold timing screws, blued hairspring, pivoted detent escapement and gold-chatoned ruby endstone on balance, beautifully engraved cases with interlaced patterns and foliage design that lines up when the watch is placed in hunter mode as seen in pics, "just stunning!" Outer case measures 53mm and weighs 35.2 grams. Inner case with movement weighs 77.8 grams for a total of 113 grams. All hinges are tight, both cases are in excellent to near mint, barely used condition! The dial is mint and looks like it was made yesterday. I set the time about 14 hours ago and it has not lost of gained a minute By turning this watch over in its outer case it can be worn either open-face or in hunter mode. Very unusual keyless winding system, specially made for this watch by Gustave Sandoz in 1896