Vacheron Constantin monopusher chronograph, 20s 18k gold cushion case, n.251050, monopusher integrated in the crown. Argenté dial, painted arabic numerals. Hand-winding movement, cal.RA13''', n.375635. Leather strap. Size: 33 x 33 mm. Accompanied by Vacheron Constantin extract from the archives. Notes: Exceedingly rare model, one of the very first chronographs ever made by Vacheron Constantin; according to our researches, less than 10 pieces have been made between 1926 and 1930.