The Sinn 903 St BE II Navigation Chronograph 903.091 is a tremendous chronograph with the impeccable Sinn quality, design and finishing level. 

The watch has all the basics right, such as 200m water resistance, scratch-resistant sapphire glass with an AR coating, a very comfortable leather strap and a solid LJP L110 mechanical (automatic) chronograph movement, which boasts 60 hours of power reserve, that is visible through the display caseback window. But it goes beyond that with DIN 8309 anti-magnetism, bezel with logarithmic scale and slide rule function and just a simply stunning vintage design.