Single-button chronograph by Universal Watch Genève, 1910s/20s. 18 kt gold case measuring 39 mm in diameter and 9.5 mm in thickness (13.5 mm with crystal). Case back and crystal with hinge opening. Martel movement. Ceramic dial with Arabic numerals, in perfect condition, even when thoroughly examined under the microscope. With two sub-dials: seconds at 6 o'clock and 30 minute counter at 9 o'clock. Red telemetric scale and internal spiral tachymetric scale. Breguet hands. Articulated lugs measuring 18.5 mm in width. Integrated chronograph push button at 6 o'clock. New, generic black leather strap, lizard effect, with gold-coloured buckle. Length: 20 cm. Lug width: 16 mm. Total watch weight: 52 g. Original Universal watch in faux leather with logo and Greca pattern in gold. Lined in red velvet and silk. Box dimensions: 18 x 10 x 2.5 cm. Very well preserved watch, with just some traces of a previous polish of the case and a slight dent level with the top hinge. This chronograph is mentioned in all the most important horology books worldwide as being the first chronograph wristwatch in the world. Insured shipping with tracking.