Valjoux 23

Foundational column-wheel chronograph movement that established the celebrated Valjoux 23/72 family. Produced from 1916 to 1974, it was a refinement of the Valjoux 22 reduced from 31.3mm to 29.5mm diameter. Features a 9-column wheel, 30 or 45-minute counter at 3 o'clock, and small seconds at 9 o'clock. Unlike the Cal. 72, it lacks the 12-hour counter at 6 o'clock. Over 126,582 examples produced. Used by Breitling, Patek Philippe (basis for Cal. 130), Heuer, Tissot, Girard-Perregaux, and many other prestigious brands. Replaced by Cal. 236 (higher beat version) in the 1970s.