The World’s Thinnest Automatic COSC & Geneva Seal Stop-Seconds Tourbillon

The World’s Thinnest Automatic COSC & Geneva Seal Stop-Seconds Tourbillon

Why Should You Care?

The watch you’re looking at from Chopard L.U.C is, in my opinion, one of the most significant tourbillons ever created in the history of watchmaking. Why, you ask? Let’s list out the reasons. First, Chopard is one of only two brands that have made a Geneva Seal and COSC-certified tourbillon; the other is Patek Philippe .

Second, the watch is the only automatic flying tourbillon that is Geneva Seal and COSC certified, period. Third, it is one of only six tourbillons in existence from major watchmakers that feature a stop-seconds function. Fourth, it has the world’s smallest and thinnest stop-seconds tourbillon mechanism, which has, in turn, allowed Chopard to create a truly elegant and infinitely wearable timepiece at 36.5mm in diameter and a mere 8.2mm in thickness. Now, let’s go through each of these reasons in more depth.

The 36.5 mm in diameter and 8.2 mm in height, Chopard L.U.C 1860 Flying T, Special Revolution equipped with a 3.5 Hz flying tourbillon; the watch boasts both the Poinçon de Genève and COSC certification (©Revolution)
The 36.5 mm in diameter and 8.2 mm in height, Chopard L.U.C 1860 Flying T, Special Revolution equipped with a 3.5 Hz flying tourbillon; the watch boasts both the Poinçon de Genève and COSC certification (©Revolution)
The L.U.C 96.24-L mechanical movement with automatic winding seen here visible through the display caseback of the L.U.C Flying T Twin, Revolution Edition Ref. 161985-1001 (©Revolution)
The L.U.C 96.24-L mechanical movement with automatic winding seen here visible through the display caseback of the L.U.C Flying T Twin, Revolution Edition Ref. 161985-1001 (©Revolution)
Central medallion with hand guilloché motif recalling the first L.U.C 1860 watch on the dial of the Chopard L.U.C 1860 Flying T, Special Revolution (©Revolution)
Central medallion with hand guilloché motif recalling the first L.U.C 1860 watch on the dial of the Chopard L.U.C 1860 Flying T, Special Revolution (©Revolution)
The L.U.C Flying T Twin, Revolution Edition is double certified with a recognition of its high craft in the Poinçon de Genève and of its chronometry in the industrial standard that is the COSC certification (©Revolution)
The L.U.C Flying T Twin, Revolution Edition is double certified with a recognition of its high craft in the Poinçon de Genève and of its chronometry in the industrial standard that is the COSC certification (©Revolution)
A close look at the tourbillon cage pinion seen here on the underside of the carriage, engaging the third wheel of the gear train; the complete weight of the tourbillon assembly is balanced and supported here (©Revolution)
A close look at the tourbillon cage pinion seen here on the underside of the carriage, engaging the third wheel of the gear train; the complete weight of the tourbillon assembly is balanced and supported here (©Revolution)
The engraved 22-carat gold bi-directional micro-rotor of the L.U.C 96.24-L (©Revolution)
The engraved 22-carat gold bi-directional micro-rotor of the L.U.C 96.24-L (©Revolution)

Why Is COSC Certification Important for a Tourbillon?

This goes to the roots of the tourbillon’s raison d’être, which is to be a chronometric device. Back in the 18th century, gentlemen of substance and style wore pocket watches in their waistcoats. In the evening, they would often hang these pocket watches on small nightstands, meaning that these timepieces spent the majority of their time in the vertical position.

But this caused a problem. It was discovered that gravity had an erosive effect on timekeeping because the hairspring powering the oscillations of the balance wheel would not breathe concentrically. Further, an uneven friction was placed on crucial pivots such as the balance staff and that belonging to the escape wheel.

It was the genius Abraham-Louis Breguet who came up with the solution. He placed all the regulating organs consisting of the balance wheel, the hairspring, the escape wheel and the lever inside of a cage which rotated once on its own axis every minute (initially this was slower), thereby averaging the errors caused by gravity. He named this extraordinary device the tourbillon or “whirlwind,” for obvious reasons.

French inventor and master watchmaker, Abraham-Louis Breguet (Image: breguet.com)
French inventor and master watchmaker, Abraham-Louis Breguet (Image: breguet.com)
On June 26, 1801, in France, Abraham-Louis Breguet earned the rights for a patent which would last for a ten year period for a new type of regulator called the “Tourbillon” (Image: breguet.com)
On June 26, 1801, in France, Abraham-Louis Breguet earned the rights for a patent which would last for a ten year period for a new type of regulator called the “Tourbillon” (Image: breguet.com)

It was the genius Abraham-Louis Breguet who came up with the solution. He placed all the regulating organs consisting of the balance wheel, the hairspring, the escape wheel and the lever inside of a cage which rotated once on its own axis every minute (initially this was slower), thereby averaging the errors caused by gravity. He named this extraordinary device the tourbillon or “whirlwind,” for obvious reasons.

In 1947, Omega made a series of 12 tourbillon wristwatch calibers for use in the famous chronometric trials. These movements designated caliber 30 I were never cased until 1987 when they were rediscovered in storage, then overhauled and placed in watches. The first commercially produced tourbillon in wristwatch format was created in 1986 when Audemars Piguet launched the exquisite, though technically flawed (the winding function wasn’t great), ultra-thin automatic wristwatch tourbillon designed by the incomparable Jacqueline Dimier.

The most expensive Omega wristwatch sold to date, the Tourbillon 30 I sold with Phillips Watches at CHF 1,428,500 (Image: philllips.com)
The most expensive Omega wristwatch sold to date, the Tourbillon 30 I sold with Phillips Watches at CHF 1,428,500 (Image: philllips.com)
Omega’s twelve Calibre 30 I participated in several trials between 1947 and 1952 and, in 1950, even achieved the highest result that had been obtained up until then within the wristwatch category in Geneva. In 1987, seven of these twelve movements were discovered by Omega and entirely rebuilt, they were then cased in gold and silver livery and offered to a select group of collectors (Image: phillips.com)
Omega’s twelve Calibre 30 I participated in several trials between 1947 and 1952 and, in 1950, even achieved the highest result that had been obtained up until then within the wristwatch category in Geneva. In 1987, seven of these twelve movements were discovered by Omega and entirely rebuilt, they were then cased in gold and silver livery and offered to a select group of collectors (Image: phillips.com)
Caseback of the Omega 30 I, sans caseback (Image: phillips.com)
Caseback of the Omega 30 I, sans caseback (Image: phillips.com)
A prime example of Jacqueline Dimier's design work is the 1986 Audemars Piguet Tourbillon, calibre 2870; Selfwinding tourbillon. 18-carat yellow gold case No 296. Calibre 2870. Model 25643BA with lug bar cover. Watch sold in 1990. Audemars Piguet Heritage Collection, Inv. 1057 (Image: audemarspiguet.com)
A prime example of Jacqueline Dimier's design work is the 1986 Audemars Piguet Tourbillon, calibre 2870; Selfwinding tourbillon. 18-carat yellow gold case No 296. Calibre 2870. Model 25643BA with lug bar cover. Watch sold in 1990. Audemars Piguet Heritage Collection, Inv. 1057 (Image: audemarspiguet.com)

But one question soon emerged, and that was, as a wristwatch spends its time in many different positions and not just in the vertical position, does a tourbillon still have any functional relevance? Well, leave it to Patek Philippe to respond to this in the way they knew best — by simply ending all debate and achieving COSC certification for their tourbillons as chronometers. For many years, and throughout the massive boom in tourbillons during the early 2000s, Patek Philippe remained the only brand with COSC certification for their tourbillons. That is despite the rise of many brands that added constant force mechanisms and chain and fusées to their tourbillons, all in the pursuit of improving chronometric performance.

Some brands even went so far to say, “We cannot send our tourbillons for COSC certification because they have no seconds hands.” Which is absolute rubbish because you can stick a seconds hand to any point on the cage that rotates precisely once every minute.

Patek Philippe remained alone in empirically proving the chronometric value of their tourbillons until Chopard L.U.C entered this realm with the Quattro Tourbillon, a tourbillon with a vibrational speed of 4Hz powered by four barrels and a power reserve of eight days, accompanied by the Geneva Seal and — drum roll please — yes, COSC certification.

Patek Philippe made no compromises in having its tourbillon watches COSC certified, this even applied to the grand complications such as the ref. 5002 Sky Moon Tourbillon, seen here in platinum (Image: christies.com)
Patek Philippe made no compromises in having its tourbillon watches COSC certified, this even applied to the grand complications such as the ref. 5002 Sky Moon Tourbillon, seen here in platinum (Image: christies.com)
The 4Hz Chopard L.U.C Quattro Tourbillon was powered by four barrels amounting to a power reserve of eight days, accompanied by the Geneva Seal and COSC certification (Image: Chopard) Quattro tourbillon
The 4Hz Chopard L.U.C Quattro Tourbillon was powered by four barrels amounting to a power reserve of eight days, accompanied by the Geneva Seal and COSC certification (Image: Chopard)

Says Karl-Friedrich Scheufele, “When we approach any complication, we want to do so with the utmost respect and authenticity. For our tourbillon, this meant that it had to be COSC certified to prove it was genuinely chronometric.”

Which is, of course, a typically polite statement from a true gentleman. However, I will go one step further to emphatically state that, to me, a tourbillon without COSC certification or the equivalent of one is a watch with a visually entertaining device but zero horological validity. This is why I have so much respect for Chopard L.U.C in that all of its watches but one (an ultra-thin watch with no seconds hand) has received both the Geneva Seal, as a testament to their refinement in finish, and COSC certification to validate their accuracy. Accordingly, the Chopard L.U.C 1860 Flying T, Special Revolution is a genuine COSC-certified chronometric masterpiece.

In our opinion the COSC-certified and Geneva Seal bearing Chopard L.U.C 1860 Flying T, Special Revolution is thusly a chronometric masterpiece (©Revolution)
In our opinion the COSC-certified and Geneva Seal bearing Chopard L.U.C 1860 Flying T, Special Revolution is thusly a chronometric masterpiece (©Revolution)
Chopard L.U.C 1860 Flying T, Special Revolution labeled diagram (©Revolution)
White triangle-shaped small seconds hand affixed to the flying tourbillon carriage crucial for COSC certification; notice also the 60 notches around the rim of tourbillon aperture serving as a seconds scale (©Revolution)
White triangle-shaped small seconds hand affixed to the flying tourbillon carriage crucial for COSC certification; notice also the 60 notches around the rim of tourbillon aperture serving as a seconds scale (©Revolution)

Why Are Stop-Seconds Tourbillons Superior to Other Tourbillons?

This follows the logic that if a tourbillon was created to be a chronometric device, then in order for it to be set accurately, it had to have a stop-seconds or hacking seconds function. Think about it this way. Back in the day when the SAS (Special Air Service) were using their 5517 MilSubs to coordinate clandestine attacks, they set their watches to the same time down to the second. Which was why it was important that their watches had a hacking function.

You couldn’t say to your commander, “Oh wait, hang on, sir, the seconds on my watch doesn’t hack, it keeps running. Can I be approximately synchronized with everyone else?” This would probably result in your being jettisoned from the cargo bay of the transport plane sans parachute. And you would deserve it, right?

So then, how is it that while there are hundreds of tourbillons in existence, there have only been six wristwatch tourbillons  with a stop-seconds function? The answer is, they are difficult to make and a pain to set up perfectly. But once they have been set up, they are clearly superior to versions without stop seconds.

Even Breguet saw the technical merit in the creating of a stop-seconds tourbillon as he made at least one example of this watch during his lifetime. This was No. 1176, the Garde Temps Four-Minute Tourbillon, dated to 1809. The first wristwatch tourbillon with a stop-seconds function dates to 2008 and was the A. Lange & Sohne Cabaret Tourbillon. This watch was discontinued in 2013 but it has been revived this year in a stunning Handwerkskunst limited edition.

Lange’s innovation was to create a Y-shaped stop-lever to stop the balance wheel, even when one arm was potentially blocked by the pillar of the cage. This same solution was used for the 1815 Tourbillon, which ingeniously incorporates a heart-cam on the tourbillon pinion to make for a zero-reset seconds hand when the tourbillon is arrested.

Abraham-Louis Breguet’s very first four-minute tourbillon and his third tourbillon watch ever made, best known as the no°1176, the timepiece is an 18K gold openface pocket chronometer with four minute tourbillon, échappement naturel, double subsidiary seconds, power reserve, stop-seconds feature and gold regulator dial; signed Breguet et Fils, No. 1176, case no. 1282, sold to Comte Potocki through Monsieur Moreau in St. Petersburg on 12 February 1809 for the sum of 4,600 Francs (Image: breguet.com)
Abraham-Louis Breguet’s very first four-minute tourbillon and his third tourbillon watch ever made, best known as the no°1176, the timepiece is an 18K gold openface pocket chronometer with four minute tourbillon, échappement naturel, double subsidiary seconds, power reserve, stop-seconds feature and gold regulator dial; signed Breguet et Fils, No. 1176, case no. 1282, sold to Comte Potocki through Monsieur Moreau in St. Petersburg on 12 February 1809 for the sum of 4,600 Francs (Image: breguet.com)
Abraham-Louis Breguet’s very first four-minute tourbillon and his third tourbillon watch ever made, best known as the no°1176, the timepiece is an 18K gold openface pocket chronometer with four minute tourbillon, échappement naturel, double subsidiary seconds, power reserve, stop-seconds feature and gold regulator dial; signed Breguet et Fils, No. 1176, case no. 1282, sold to Comte Potocki through Monsieur Moreau in St. Petersburg on 12 February 1809 for the sum of 4,600 Francs (Image: breguet.com)
Abraham-Louis Breguet’s very first four-minute tourbillon and his third tourbillon watch ever made, best known as the no°1176, the timepiece is an 18K gold openface pocket chronometer with four minute tourbillon, échappement naturel, double subsidiary seconds, power reserve, stop-seconds feature and gold regulator dial; signed Breguet et Fils, No. 1176, case no. 1282, sold to Comte Potocki through Monsieur Moreau in St. Petersburg on 12 February 1809 for the sum of 4,600 Francs (Image: breguet.com)
The movement for the 1176 is the Cal. 24''' gilded brass movement, with semi-elliptical backplate, reverse fusée with maintaining power, échappement naturel of unusual design with 12-toothed and 3-toothed escape wheels, the lever with single banking spring allowing even rest on both escape wheels, three arm bimetallic compensation balance with an oscillation rate of 21,600 vibrations per hour, blued steel balance spring with terminal curve, all mounted in the two-arm tourbillon cage driven from the second wheel pinion and revolving once every four minutes; the tourbillon carriage is stopped by a lever (seen here on the bottom right) in the bezel, allowing the precise setting of the time, case no. 1282 by Amy Gros (Image: breguet.com)
The movement for the 1176 is the Cal. 24''' gilded brass movement, with semi-elliptical backplate, reverse fusée with maintaining power, échappement naturel of unusual design with 12-toothed and 3-toothed escape wheels, the lever with single banking spring allowing even rest on both escape wheels, three arm bimetallic compensation balance with an oscillation rate of 21,600 vibrations per hour, blued steel balance spring with terminal curve, all mounted in the two-arm tourbillon cage driven from the second wheel pinion and revolving once every four minutes; the tourbillon carriage is stopped by a lever (seen here on the bottom right) in the bezel, allowing the precise setting of the time, case no. 1282 by Amy Gros (Image: breguet.com)
A. Lange & Söhne launched the Cabaret Tourbillon in 2008, in pink gold and platinum, and with it the calibre L042.1 which showcased Lange's one-minute tourbillon with a patented stop seconds mechanism (Image: christies.com)
A. Lange & Söhne launched the Cabaret Tourbillon in 2008, in pink gold and platinum, and with it the calibre L042.1 which showcased Lange's one-minute tourbillon with a patented stop seconds mechanism (Image: christies.com)
A graphic representation of how the Lange stop seconds mechanism works on the tourbillon by directly acting on the balance bridge (Image: A. Lange & Söhne)
A graphic representation of how the Lange stop seconds mechanism works on the tourbillon by directly acting on the balance bridge (Image: A. Lange & Söhne)
The stop lever mechanism used by Lange to stop the tourbillon balance wheel when the crown is pulled out (Image: langepedia.com)
The stop lever mechanism used by Lange to stop the tourbillon balance wheel when the crown is pulled out (Image: langepedia.com)
The A. Lange & Söhne 1815 Tourbillon with Enamel Dial
The A. Lange & Söhne 1815 Tourbillon with Enamel Dial
Stop seconds and zero-reset mechanism in the 1815 Tourbillon: highlighted (from left) are the spring hammer, heart-cam with seconds hand and balance wheel stop lever
Stop seconds and zero-reset mechanism in the 1815 Tourbillon: highlighted (from left) are the spring hammer, heart-cam with seconds hand and balance wheel stop lever
The y-shaped stop lever mechanism used by Lange in the 1815 Tourbillon
The y-shaped stop lever mechanism used by Lange in the 1815 Tourbillon

Moritz Grossmann, another brand based in Glashütte, Germany, also has a stop-seconds tourbillon — leave it to the Germans to be obsessed with precision — and uses a tiny brush made from human hair that acts as a brake on the balance wheel. If the pillar of the cage gets in the way, the brush will split and still contact the balance wheel.

The Moritz Grossmann Benu Tourbillon is equipped with a stop seconds mechanism that uses a small bunch of human hairs obtained from the head of the head of the brand, Ms Christine Hutter (Image: Moritz Grossmann)
The Moritz Grossmann Benu Tourbillon is equipped with a stop seconds mechanism that uses a small bunch of human hairs obtained from the head of the head of the brand, Ms Christine Hutter (Image: Moritz Grossmann)
The small bunch of human hairs obtained from the head of brand CEO, Ms Christine Hutter used to arrest the balance wheel on the Moritz Grossmann Benu Tourbillon (Image: Moritz Grossmann)
The small bunch of human hairs obtained from the head of brand CEO, Ms Christine Hutter used to arrest the balance wheel on the Moritz Grossmann Benu Tourbillon (Image: Moritz Grossmann)

The Grönefeld Brothers make a watch called the Parallax Tourbillon, which features a massive seconds hand that in combination with the raised outer seconds track is meant to eliminate parallax error; hence, the watch’s name. When you push in the crown here to the setting mode in this watch, a stop lever comes into play, acting on the tourbillon cage and causes both the  seconds hand and tourbillon cage to stop at precisely 12 o’clock to allow for a pseudo “zero-reset” type of accurate time setting.

The Grönefeld Parallax tourbillon features a “flying” tourbillon with a large central seconds hand, stop seconds, power reserve indicator (Image: Grönefeld)
The Grönefeld Parallax tourbillon features a “flying” tourbillon with a large central seconds hand, stop seconds, power reserve indicator (Image: Grönefeld)
The Caliber G-03 of the Grönefeld Parallax tourbillon features a direct drive seconds hand (Image: Grönefeld)
The Caliber G-03 of the Grönefeld Parallax tourbillon features a direct drive seconds hand (Image: Grönefeld)
Highlighted here is the Caliber G-03's stop lever that causes the tourbillon cage and seconds hand to come to a stop at precisely 12 o'clock when the watch is set into settings mode (Image: Grönefeld)
Highlighted here is the Caliber G-03's stop lever that causes the tourbillon cage and seconds hand to come to a stop at precisely 12 o'clock when the watch is set into settings mode (Image: Grönefeld)

The Montblanc ExoTourbillon features a deconstructed tourbillon where the cage, hairspring and balance sit at different levels. As such, the stop-seconds lever can directly contact the balance.

Montblanc's Exotourbillon as seen on the Heritage Chronometrie Exo Minute Chrono VdG Dia LE 25 (Image: Montblanc)
Highlighted here is the stop level arm that arrests the balance wheel on Montblanc's Exotourbillon (Image: Montblanc)
Highlighted here is the stop level arm that arrests the balance wheel on Montblanc's Exotourbillon (Image: Montblanc)

IWC’s flying tourbillon also has a hacking function. When you pull out the crown, a pair of brake arms descend on the balance wheel. But what happens if the pillars of the cage get in the way? IWC have very cleverly mounted these brake arms on springs, so they are able to flex and move around the pillars should they be in the way — a typically ingenious solution from Schaffhausen.

The Portugieser Chronograph Tourbillon Retrograde is an instance of IWC tourbillon wristwatches that uses the brand's own take on the stop-seconds tourbillon mechanism (Image: IWC Schaffhausen)
The Portugieser Chronograph Tourbillon Retrograde is an instance of IWC tourbillon wristwatches that uses the brand's own take on the stop-seconds tourbillon mechanism (Image: IWC Schaffhausen)
IWC's take on the stop-seconds tourbillon mechanism works as such: When the crown is pulled out, the mechanism is stopped by two levers that grip the balance rim like a set of pliers (Image: IWC Schaffhausen)
IWC's take on the stop-seconds tourbillon mechanism works as such: When the crown is pulled out, the mechanism is stopped by two levers that grip the balance rim like a set of pliers (Image: IWC Schaffhausen)

It is not lost on me that of the other five brands that have incorporated the stop-seconds function into their tourbillon wristwatches, two are German, one is Dutch, and one is made in Switzerland but its parent company is based in Hamburg, Germany, and one sits at the very border between Switzerland and Germany. Perhaps the proximity to Germany and its culture for ultra-precision has something to do with the desire to make a better tourbillon.

But this is where Chopard L.U.C has again brought a game-changing level of innovation to the stop-seconds tourbillon. Because, here the brake function is not applied to the balance but instead to the cage, somewhat like that in the case of the Parallex Tourbillon. Further, because the cage of the tourbillon is exactly the same diameter as the tourbillon aperture on the dial, the brake function is hidden from view so that it is, in effect, a mysterious stop-seconds tourbillon.

The brake function on the L.U.C 96.24-L is not applied to the balance but instead to the cage, somewhat like that in the case of the Parallex Tourbillon; further, because the cage of the tourbillon is exactly the same diameter as the tourbillon aperture on the dial, the brake function is hidden from view so that it is, in effect, a mysterious stop-seconds tourbillon (©Revolution)
The brake function on the L.U.C 96.24-L is not applied to the balance but instead to the cage, somewhat like that in the case of the Parallex Tourbillon; further, because the cage of the tourbillon is exactly the same diameter as the tourbillon aperture on the dial, the brake function is hidden from view so that it is, in effect, a mysterious stop-seconds tourbillon (©Revolution)

This is what happens when you pull the crown out on the Chopard L.U.C 1860 Flying T, Special Revolution. The tourbillon cage on which the seconds hand is mounted stops dead in its tracks. The balance wheel will power down by oscillating a few times then come to a standstill. But what is important to understand is that these oscillations have no effect on the timekeeping accuracy of the watch. Why?

OK, let’s explain how this tourbillon works. The first wheel, which is powered by the barrel engages the center wheel, which turns the cannon pinion that drives the minute and hour wheel. The center wheel turns the third wheel, which engages the pinion of the tourbillon cage. The cage drives the escape wheel around a fixed fourth wheel, which powers the lever which causes the balance to oscillate.

A energy flow in a typical tourbillon going train assembly: The mainspring (A) powers the centre wheel (B) which powers the going train which powers the third wheel (C) which powers the cage (D) which causes the escape wheel’s pinion to turn against the fixed fourth wheel (E) which powers the escape wheel (F) which powers the lever (G) which impulses the balance (H)
A energy flow in a typical tourbillon going train assembly: The mainspring (A) powers the centre wheel (B) which powers the going train which powers the third wheel (C) which powers the cage (D) which causes the escape wheel’s pinion to turn against the fixed fourth wheel (E) which powers the escape wheel (F) which powers the lever (G) which impulses the balance (H)

When you stop the cage, you stop the entire motion works of the gear train, meaning the minute and hour hands cannot turn — time is frozen in place. When you lift the brake off the cage, it is the third wheel being driven by the barrel through the other wheels that starts the balance again. In fact, you could make an argument that stopping the cage rather than the balance is a much less aggressive way to create a stop-seconds tourbillon, because the balance wheel is delicately regulated and poised to oscillate uniformly.

The rapidity with which the balance starts to oscillate again is based purely on the quality of torque coming from the mainspring and flowing through the gear wheels. And in this case, the L.U.C 1860 Flying T, Special Revolution wins again as it has the advantage of being powered by a pair of stacked twin barrels.

Ultimately, not only is this Chopard watch a remarkable feat of technical innovation, but it is also extraordinary in terms of how wearable it is. The IWC tourbillon watch with hacking function is 16.9mm in height. Compare this with the L.U.C 1860 Flying T, Special Revolution’s incredible 8.2mm in height. The fact that this watch is an automatic, micro-rotor driven, stop-seconds flying tourbillon with Geneva Seal and COSC certification makes it, to me, the most extraordinary timepiece in the tourbillon category hands down.

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