Navitimer B01 Chronograph 41 Stainless Steel / Mint Green / Bracelet

In Context

At 41 mm it is sized to the current mainstream: 40 mm is the median across every watch measured in this catalogue. At 13.6 mm it is a tall case, and it will catch on a cuff. The case back is open, so the movement is visible without taking the watch apart, and the sapphire crystal will resist everything short of deliberate abuse. Rated to 30 m, it is protected against rain and splashes and nothing beyond that.

The movement winds itself from the motion of your wrist. 70 hours of reserve is enough to set it down on Friday evening and find it still running on Monday. At 28,800 vph the seconds hand advances 8 times a second.

AB0139211L1A1 stands on its own in this catalogue — no other reference here shares its base number. It pairs a green sunburst dial with a stainless steel case. Beyond the time it carries a chronograph.

The B01 is Breitling's in-house chronograph, launched in 2009 and now inside 861 watches in this library, more than any other Breitling movement. 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](/calibers/breitling-caliber-b03) split-seconds, the [B04](/calibers/breitling-caliber-b04) second time zone and the [B05](/calibers/breitling-caliber-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](/calibers/breitling-caliber-b20). The reference number tells you it is fitted: an AB01 prefix is a steel case with a B01, as the [reference-number guide](/blog/how-to-read-a-watch-reference-number) explains. In this library the movement sits under 194 [Navitimers](/brands/breitling/navitimer), 175 [Chronomat B01 44s](/brands/breitling/chronomat-b01-44), 136 [Chronomat B01 42s](/brands/breitling/chronomat-b01-42), 87 [Transoceans](/brands/breitling/transocean), 67 [Premiers](/brands/breitling/premier), 59 [Avengers](/brands/breitling/avenger) 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](/calibers/breitling-caliber-13) is the ETA-based chronograph it replaced at the top of the range, and the [Valjoux 7750 piece](/blog/the-valjoux-7750-family) explains what that older architecture was.

860 other watches in the library run the Breitling Caliber B01.

Breitling

Transocean Chronograph Stainless Steel / Reverse Panda / Calf / Pin

AB015212/BF26/437X/A20BA.1 · 43 mm

Breitling

Chronomat 41

CB014012BA53378C · 41 mm

Breitling

Chronomat 44 Stainless Steel / Silver / Rubber

AB011011/G684/131S · 44 mm

Breitling

Chronomat B01 42 NFL Denver Broncos

AB01342B1O2S1 · 42 mm