Jaeger-LeCoultre Releases The Master Ultra Thin Power Reserve

by Sameera Gamage

The Master Ultra Thin collection gets a new update with the brand-new reinterpretation of the Power Reserve model!

Jaeger-LeCoultre’s Master Ultra Thin Collection is marketed as the quintessential dress watch for the modern gentlemen. The collection combines the brand’s philosophy of fine luxury watchmaking and designs that exude timeless beauty, matched equally by the movement’s mechanical mastery.

Jaeger-LeCoultre has taken all these qualities that are the core ingredients of the Master Ultra Thin Collection and designed the latest interpretation of the Master Ultra Thin Power Reserve. This latest addition to the collection comes with a subtly modernised case and dial design, a new gradient midnight blue sunray dial, and a significantly increased power reserve.

Jaeger-LeCoultre artisan’s constructing the dial of the all-new Master Ultra Thin Power Reserve

The power reserve function, one of the core elements of this latest model, is a signature complication of Jaeger-LeCoultre. The function was first introduced in 1948 through the movement calibre 481. The Powermatic came with a distinctive red-and-white indicator and was the world’s first self-winding timepiece with a power reserve gauge. Due to this design, it quickly became a key model for the manufacturer in the early 1950s.

The Master Ultra Thin Power Reserve retains all the signature details of the Master Ultra Thin collection, including the elongated shape of the applied hour markers, the Dauphine hands for the hour and minutes and the beautifully stylish and polished case. These details make this an impressive dress watch, all the more appealing with the ultra-thinness of the case.

All-new Master Ultra Thin Power Reserve on the wrist

This new model, however, does come with some subtle and not-so-subtle design variations. Compared to the two existing Master Ultra Thin Power Reserve models in Jaeger-LeCoultre’s current Master Ultra Thin Collection in both stainless steel and pink gold (750/1000 18 carats), this new addition by far stands out the most for its colour scheme, elegance and more refined appearance.

While the case sizes remain the same throughout all the models for the Master Ultra Thin Power Reserve at 39mm, the case design has been modernised for this timepiece, with revised proportions and slimmer, more elongated lugs that make it even more comfortable on the wrist. The main aesthetic changes on the dial occur with changes to the sub-dials. Jaeger-LeCoultre has refined the dial architecture while retaining the balanced symmetry to keep the previous versions’ proportionate aesthetics.

Close-up details of the new dial on the Master Ultra Thin Power Reserve. The power reserve indicator has been significantly modified from the previous generation’s models.

The sub-dials have increased in size, which allows the complications of the date at 3 o’clock, small seconds display at 6 o’clock, and the power reserve indicator at 9 o’clock all the more legible. Other notable changes to the subdials include the removal of the inscription “RESERVE DE MARCHE” underneath the power reserve indicator and adding the seconds track on the small seconds display. The power reserve indicator scale has also changed to measure in quarterly increments, with the first quarter also being highlighted in red to indicate to the user the power levels are low quickly.

While these changes may be subtle, they add more detail and character to the watch. I do like the coloured power reserve indicator, as not only does it add an extra touch of colour to the dial, but it also gives the wearer a noticeable power reserve reading. The pink gold hands and hour indices also contrast dramatically with the gradient midnight blue of the sunray dial, while the matte blue texture of the three subdials breaks up the gradient finish of the dial to stand out on their own.

In line with La Grande Maison’s pursuit of timekeeping precision, the Manufacture constantly improves its in-house calibres in line with advancing technology. This new version of the Master Ultra Thin Power Reserve comes with the latest Calibre 938 movement, which has now been significantly revised to offer a greater power reserve. With the movement retaining the high frequency of 4Hz (28,800 VpH), the power reserve has increased to 70 hours.

Installing the winding rotor on the latest generation calibre 938 movement.

Jaeger-LeCoultre states that regarding this new generation calibre, “this significant gain in power reserve has been achieved without adding to the size of the calibre, which remains 4.9mm thick. The mainspring barrel was redesigned, some key components are now made of silicon, which makes energy transmission smoother by reducing the friction of the moving parts, and other minor changes have been made to bring greater reliability.”

The Master Ultra Thin Power Reserve comes with a dark navy blue alligator leather strap, which matches the midnight blue colour of the dial nicely. However, if a navy-coloured strap, or even a leather strap, isn’t your choice, it can be quickly interchanged to a more preferred styling with the wide range of straps Jaeger-LeCoultre has available.

The all-new Master Ultra Thin Power Reserve with the navy blue alligator leather strap on the wrist shot.

This latest update to an elegant yet sophisticated timepiece is the best among the Master Ultra Thin Power Reserve models. What stands out for me is the combination of the pink gold against the midnight blue gradient dial, giving it that great luxury and aesthetic appeal. To match these upgrades in aesthetics, the movement has been redesigned to give a greater power output, from the previous model’s power reserve of 43 hours to now 70 hours. This latest re-interpretation of the Jaeger-LeCoultre Master Ultra Thin Power Reserve is an ideal candidate for the perfect dress watch (read our article on what makes for a great dress watch here!).

Reference: Q137258J


  • Case: 39mm x 8.95mm thick
  • Case Material: Pink Gold 750/1000 (18 carats)
  • Dial: Gradient blue sunrayed with matte blue sub-dials
  • Crystal: Sapphire crystal with anti-reflective coating
  • Water resistance: 50m (5 Bar)
  • Movement: Automatic Calibre 938
  • Movement Frequency: 4Hz (28,800 VpH)
  • Power reserve: 70 hours
  • Bracelet: Navy-coloured alligator leather strap with pink gold buckle.

Australian Recommended Retail Price: AUD $34,200

Availability: Non-Limited. Available now through Jaeger-LeCoultre boutiques.

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