Founded in 1961 in Frankfurt am Main, Germany, Sinn Spezialuhren is known for its instrument watches engineered for professional use and technical reliability. The 903 collection continues the legacy of classic pilot chronographs with slide rule bezel functionality.

The Sinn 903 ST is a traditional pilot’s chronograph combining aviation heritage with robust German engineering. The watch features a 41 mm stainless steel case paired with a black dial. Luminous hands, applied hour markers, and the characteristic slide rule scale ensure excellent legibility and functional depth. Powered by the automatic Sellita SW500 movement, it offers a power reserve of approximately 48 hours, a frequency of 28,800 vph, and functions including chronograph, date. A sapphire crystal with anti-reflective coating protects the dial, while the bidirectional slide rule bezel enables aviation calculations. Water resistance is rated at 100 meters. The watch is fitted on a black leather strap with a pin buckle.

This 903 ST is in near mint condition and comes as a full set.