ZENITH EL PRIMERO CHRONOMASTER Zenith, "ChronoMaster Open - El Primero, Automatic," Ref. 03 1260 4021. Made circa 2003. Fine, large, self-winding, water-resistant, stainless steel wristwatch with square button chronograph, register, power reserve indication, tachometer, visible escapement and a Zenith stainless steel double deployant clasp. Two-body, polished, stepped bezel and lugs, transparent Case back with 8 screws, sapphire crystals. Guilloche silver with applied white gold radial Roman numerals and dart indexes on a plain reserve, outer 1/5th seconds track and tachometer scale, subsidiary dial for the 30-minute register, sector for the power reserve indication, large aperture to view the escapement and 4th wheel with three-arm seconds hand. White gold dauphine hands. Cal. 4021, rhodium-plated, oeil-de-perdrix decoration, 39 jewels, straight-line lever escapement, monometallic balance, shock absorber, self-compensating flat balance spring.