Caliber B01

About the Breitling Caliber B01

It is a column-wheel chronograph with a vertical clutch, which means the seconds hand starts without the stutter of a horizontal coupling and can run permanently without wearing the going train. Two barrels are not needed: a single one gives 70 hours, the balance beats at 28,800 vph, and every B01 is certified by the COSC. It was designed as a base with room on top, and the B03 split-seconds, the B04 second time zone and the B05 world timer are all B01s with a module added. Breitling also supplies it to Tudor as the MT5813, in exchange for the three-hand movement Breitling sells as the B20.

The reference number tells you it is fitted: an AB01 prefix is a steel case with a B01, as the reference-number guide explains. In this library the movement sits under 194 Navitimers, 175 Chronomat B01 44s, 136 Chronomat B01 42s, 87 Transoceans, 67 Premiers, 59 Avengers and the Chronomat 41 and Super Chronomat. Cases run from 40 mm to 50 mm, with 44, 42 and 43 mm the most common, and 205 of the 861 references are limited editions.

The Caliber 13 is the ETA-based chronograph it replaced at the top of the range, and the Valjoux 7750 piece explains what that older architecture was.