Considering one's increased heart rate upon seeing this watch, it is easily understandable why it features a pulsometer. The Longines reference 3504 is amongst the rarest and most desirable of all Longines chronograph models made even more desirable and rare thanks to its hardly ever seen black glossy dial with pulsations scale and extraordinary condition.

It is incredible to think that this watch is over 60 years of age.

The present Longines chronograph houses the legendary caliber 13ZN, considered by connaisseurs as one of the most beautiful chronograph movements ever developed. This legendary manual wind chronograph was launched in the 1930s and was in production until the beginning of the 1970s. The 13ZN was designed as a flyback chronograph, where a user can quickly reset the chronograph seconds hand to zero while it’s still running. Longines initially intended for these wristwatches to be used as tools for military personnel and aviators. In the present watch it was destined for medical use thanks to its pulsation scale.

In unmolested condition, the case maintains strong crisp proportions, thick lugs and beautifully preserved brushed and polished surfaces. The numbers engraved on the case back and on the inner lug are perfectly crisp. The black glossy dial with gilt printing and bold Arabic numerals has amazing charisma.

This watch is furthermore published in John Goldberger’s new book dedicated to Longines, proof not only of its superb quality but also of its historical importance.