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MB&F Raises the Complication Stakes with the Improved LM Sequential Flyback Platinum

The LM Sequential flies back in time aesthetically and cruises forward mechanically, adding flyback functionality to the already impressive mix.

| By Rebecca Doulton | 5 min read |

The aphorism “if it ain’t broke, don’t fix it” is not often used by watchmaker Stephen McDonnell, the mastermind behind MB&F’s most complex timepieces enhanced with his innovative technological breakthroughs. Responsible for the 2015 LM Perpetual and the LM Sequential EVO, fans of MB&F’s wonderful watches will be delighted to learn that Stephen McDonnell is back. This time, McDonnell ups the functionality of his award-winning chronograph calibre by incorporating a flyback function. However, for this new souped-up edition of 33 pieces, MB&F restages the complications in a more classical Legacy Machine capsule. Soaring in a platinum case with a sky-blue dial plate, the LM Sequential Flyback is the stuff watchmaking dreams are made of.

The LM Sequential EVO, released in 2022, was MB&F’s first chronograph and 20th calibre, and in true MB&F style, it had to be mind-blowing. Calling on a longstanding MB&F friend and watchmaking wizard, Stephen McDonnell, the LM Sequential EVO he designed blew conventional chronographs out of the water.

MB&F Legacy Sequential EVO Chronograph Split Seconds Lap Timer Stephen McDonnell
The Legacy Sequential EVO, the first chronograph of MB&F, released in 2022.

Trained as a theologist before becoming a watchmaker, McDonnell’s approach to creating a chronograph movement was unconventional. Instead of asking ‘how’, his approach was to determine all the situations in which a chronograph might come in handy. Fitted with two column-wheel chronograph mechanisms linked to the same oscillator, which could be activated simultaneously, it opened a window to countless timing possibilities. Augmenting the role played by the traditional operating lever, McDonnell equipped the movement with his revolutionary Twinverter switch. The ability to toggle instantly between chronograph operating models increased the versatility of the complication, allowing you to select four different timing modes – independent timing, simultaneous or split-second timing, sequential or lap-timer and cumulative (v. useful for timing chess matches) – and invert the start/stop status of each chronograph. Don’t miss Brice’s in-depth coverage to understand the different applications of these four modes.

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Above: a comparison between the Legacy Sequential EVO (left) and the new LM Sequential Flyback (right)

With 585 components, a suspended, oversized balance wheel and a smorgasbord of timing options, MB&F decided to house this insanely complex creature inside its more resilient 44mm zirconium EVO case fitted with a shock-absorbing dampener and water-resistant to 80m. Touted as the brand’s case for outdoor adventures, I am not sure how many owners of the LM Sequential chronograph will admit to having used it for a cross-country cycle.

Classic case, Flyback movement

Building on the already mind-bogglingly sophisticated movement, the LM Sequential welcomes a flyback on board, a function initially conceived for pilots. Developed in the 1930s for pilots, the flyback or “retour en vol” eliminated the time-wasting stop, reset and restart phases of a chronograph that could accumulate and result in dangerous navigation errors. The flyback solved the problem with its simultaneous single press to activate stop, reset and restart.

It turns out, though, that McDonnell’s original prototype for the LM Sequential EVO included a flyback but was put on hold due to the additional time needed for R&D and testing. After two years of testing and absolute secrecy, the LM Sequential Flyback is ready, meaning there are now five separate modes for timing.

While the dial layout is identical to the LM Sequential EVO, the new model adopts the more classical Legacy Machine habitat. Still bristling with five pushers, the 44mm platinum case has a height of 18.2mm, longer screwed lugs and features brightly polished surfaces with brushed case flanks. Another distinguishing feature is the engraved inscription on the lower pushers that now reads FLYBACK. Although the crown is screwed-down, the case has a lower water-resistance of 30 metres.

The LM Sequential Flyback equips both chronographs with flyback functionality and operates as follows: the left chronograph is activated via the start/stop pusher at 10 o’clock and reset/flyback at 8 o’clock; the right chronograph operates identically but with the pushers at 2 and 4 o’clock. The fifth pusher on the case at 9 o’clock is the Twinverter or ‘magic button’ that controls both chronograph systems and operates as a binary switch that inverts the current start/stop status of both. If the two chronographs are stopped, pressing the magic button causes them to start simultaneously, and if they are both running, the Twinverter makes them stop. Elapsed times are displayed on the four sub-dials: two 30-minute counters at 11 and 1 o’clock and two larger 60-second counters at 9 and 3 o’clock.

The LM’s more traditional traits can be appreciated on the dial with its impressive balance wheel suspended above the four chronograph counters with their white lacquered rings and blued hands. Unlike the EVO, the domed white lacquered time sub-dial at 6 o’clock with Roman numerals is placed over the twin chronograph counters, not under and tilted towards the wearer, thanks to conical gears. The sky-blue mainplate provides a beautiful celestial background.

A single movement with two independent chronographs demands a lot of power. McDonnell’s ingenuity addresses the problem using his innovative and patented jewelled vertical clutches, which reduce friction and prevent the flyback from producing the return-to-zero block. A special jewelled roller was developed for the flyback mechanism, allowing the Sequential calibre to outperform conventional chronographs in energy efficiency and precision.

The fully integrated dual chronograph flyback manual-winding movement now has 619 components. Still, it maintains its 3Hz frequency and 3-day power reserve thanks to the double mainspring (the power reserve indicator can be seen in the lower part with a blued hand). Beautifully decorated with hand-finishings, the darkened bridges (NAC finish) contrast with the polished bevels and bright rubies.

Availability & Price

The LM Sequential Flyback Platinum is a limited edition of 33 pieces and retails for CHF 188,000, EUR 192,000 or USD 218,000 (all prices excl. taxes). For more information, please consult

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