On the wrist, its size dominates one’s first impression; however, it is balanced by the excellently constructed tonneau-shaped case. From this perspective, it can be compared to the Heuer Autavia, although that one has a smaller diameter. The robust case features polished and brushed finish.
The case is 44mm in diameter 45mm lug tip to lug tip and with a 22mm lug spacing.
Black Bakelite Original 1972 bezel, bi-directional 60 click classic divers count up bezel,
Tritium lume triangle at 12 and it's easy to spot an original bezel with a later service replacement the earliest bezels have rounded edges whilst latter tringles are sharper points.
Like any other diver dial read apparatus or pilots dashboard instruments (and in this case both!), The Tool watch is designed to give maximum read clarity at a glance.
The crisp white detail on the stark black backdrop achieve this excellently,
with subsidiary dials for the 12-hour and 30-minute register and the constant seconds. Around the dial is a chapter ring with markers for the minutes, seconds and 1/5th seconds. There is an outer tachometer scale and finally, the aperture for the date is positioned between 4 and 5. Despite all this information, the dial is not cluttered at all.
All this visible under the original Saphire glass crystal.
Original ZENITH "Big Link" bracelet, one of Two variation bracelets originally sold with the "Pilot Diver" the most common being the Gay Freres "lobster" band Rarity aside I prefer the Zenith Bracelet
The El Primero
It was in 1962 that the basics of the El Primero movement first took shape on the drawing board. The idea was simple: to create an iconic watch that would be launched in time for the centenary of the Manufacture in 1965. The idea was simple, but the technical specifications were not. It was to be the first automatic chronograph ever. Better still, the caliber was to be fully integrated and designed as an inseparable whole. There would be no additional module, but instead a construction built around a column wheel and a central rotor mounted on ball bearings. It would also need to beat at a high frequency in order to be the world’s most accurate chronograph. To complicate matters still further, the movement was to be miniaturised and equipped with a date mechanism. All these factors amounted to an equation so complex that it would take seven years to solve it – four years past the anniversary date.