Zenith's El Primero calibre was the first ever automatic chronograph and still the only one capable of measuring short times to the nearest tenth of a second – in 1970, it was fixed to the landing gear of a Boeing 707 and, despite the high altitudes and atmospheric pressures, remained accurate upon landing - save for the inevitable time difference. This Swiss-engineered timepiece took nine months to make, in a painstaking process involving a series of 2,500 intricate operations. It's fitted with a tachymetric scale to measure speed, and a 400B automatic column-wheel movement which operates at 36,000 Vph and can be seen through the rear of the case's sapphire crystal exhibition window. The sturdy rubber strap rounds off its masculine, sporty feel and is perforated for comfortable aeration. We offer a two-year warranty for all working parts and manufacturing faults for luxury watches. Call our Customer Care team for more information.