ZENITH El Primero, Automatic, Chronomaster Open Anniversary, Zenith El Primero 40th anniversary collection, Ref. 03.1260.4021/69.C505, limited edition no. 92/169, movement no. 289414, manufactured in 2009 for the 40th anniversary of the model (1969-2009) A very fine and rare, limited edition, large, water-resistant, certified chronometer, stainless steel chronograph wristwatch with guilloche silvered dial, applied anniversary logo, aperture to see the balance and escapement, tachymeter scale, 30-minute register, power reserve indication, rectangular chronograph pushers, leather strap and a stainless steel Zenith deployant clasp. Fitted with a Cal. 4021, mechanical, self-winding, 39 jewels, visible through the sapphire-set case back secured by eight screws, sapphire crystal. Dial, case and movement signed. Diam. 45.20 mm. Thickness 14.50 mm. Accompanied by a Zenith presentation box. The Zenith El Primero Chronomaster Open XXT 40th Anniversary, reference 03.1260.4021/69.C505, was introduced around 2009 to commemorate the 40th anniversary of Zenith's groundbreaking El Primero movement, which debuted in 1969 as one of the first automatic chronograph calibers.