Zenith, El Primero, ref. 02.2310.400, a stainless steel bracelet watch, circa 1999, automatic chronograph movement, 31 jewels, cal. 400, black dial, applied luminous dot markers, luminous pointed baton minute and Mercedes hour hands, centre chronograph hand, subsidiary dials for constant seconds, 30 minute and 12 hour recording, date aperture between 4 and 5 o'clock, rotating bezel with black insert, with Arabic numeral 10 minute track, screw down crown and pushers, screw down case back, on a Zenith stainless steel bracelet with fold over clasp, case back, dial, movement, crown and clasp signed, accompanied by a Zenith box, guarantee card, two spare links, a spare white dial and outer card packaging, diameter 40mm, bracelet 20cm The El Primero gains it's name from the word Esperanto, meaning 'the first'. In 1969 the race was on to build the first automatic chronograph movement. On the 10th January, Zenith and it's partner Movado were able to show a working prototype at a press conference in Geneva. This was ahead of the combined competition of Breitling, Heuer-Leonidas, Hamilton/Büren and Dubois Dépraz, who announced theirs in March. This ground braking movement has been used by other brands, including Rolex who used a modified version in the Daytona.