The Tudor-Breitling partnership
In 2017, Tudor and Breitling announced a movement-sharing agreement that surprised the watch world. Tudor would supply Breitling with the MT5612 three-hand-date architecture, rebadged as Breitling Cal. B20 for use in the Superocean Heritage and other Breitling lines. In return, Breitling would supply Tudor with its B01 chronograph caliber, rebadged as Tudor MT5813 for use in the Tudor Heritage Chrono. The partnership made commercial sense for both: Breitling needed an in-house three-hand caliber it did not have, and Tudor needed an in-house chronograph beyond the older ETA-base Heritage Chrono.
What the B01 architecture brings
The Breitling B01 (released 2009) is Breitling's first wholly in-house chronograph, designed by Breitling's engineering team for the modern Chronomat. Column-wheel + vertical clutch architecture (no chrono jitter), 70-hour power reserve, 4 Hz, integrated chronograph (not a module bolted onto a base). The architecture is broadly comparable to the Rolex 4131 in technical level, slightly above the Valjoux 7750 on every spec line. As the MT5813, Tudor refines the B01 with: free-sprung balance (Tudor adds variable-inertia weights for precision regulation), silicon hairspring, and Tudor-specific finishing (rotor decoration, bridge styling).
The Kenissi facility
The MT5813 is manufactured at Kenissi, the Tudor-owned movement facility in Le Locle. Kenissi opened in 2016 as Tudor's in-house manufacture; in 2019 it became jointly-owned with Chanel, and supplies movements to Tudor, Chanel (J12 Caliber 12.1 base), Breitling (the partnership), and Norqain. The MT5813 specifically is finished, regulated, and tested at Kenissi with Tudor's in-house quality control before going into Tudor watches; the underlying B01 base parts come from Breitling.
Watches it powers
The MT5813 powers the modern Tudor chronograph line. Black Bay Chrono ref. M79360N (2017+, the canonical MT5813 watch, panda or reverse-panda dial, 41 mm). Black Bay Chrono S&G ref. M79363N (steel and gold). Heritage Chrono ref. M70330N and family. The Pelagos line uses a different in-house Tudor caliber (the MT5612 family); the chronograph line is MT5813-only. The Black Bay Chrono is the most-popular MT5813 reference; retail around CHF 5,400 in 2026, AD waits typically 6-18 months for hot reference variants.
How it compares to the Rolex 4131
The MT5813 and the Rolex 4131 are conceptually similar: both column-wheel + vertical-clutch automatic chronographs at 4 Hz with 70+ hour reserves and free-sprung balances. Differences: the 4131 is wholly Rolex-developed and -manufactured; the MT5813 starts from a Breitling B01 base. The 4131 has Rolex's Chronergy escapement and Parachrom Bleu hairspring; the MT5813 has a silicon hairspring. The 4131 retails in a CHF 15,000+ Daytona; the MT5813 retails in a CHF 5,400 Black Bay Chrono. For 1/3 the price, the MT5813 delivers 90% of the chronograph engineering. This is the modern Tudor value proposition: serious in-house mechanicals at much-easier-to-buy prices.
Service notes
Service for an MT5813 watch runs CHF 800-1,000 at Tudor, with the 2-year warranty. Recommended interval: 10 years, same as the broader MT-series family. The MT5813 is serviced through the Rolex/Tudor service network worldwide. Independent service is increasingly possible as Kenissi-trained watchmakers become available outside the brand network, but parts access for the silicon hairspring, free-sprung balance, and the column-wheel chronograph mechanism remains restricted. The watch comes back regulated to -4/+6 sec/day COSC spec across all positions.
