TAG Heuer flexes its research and development muscles again with the performance-oriented Monaco Split-Seconds Chronograph Air 1.

Using the iconic square chronograph as a base, the brand’s engineers took inspiration from its Formula 1 partnership to explore new manufacturing techniques for this 30-piece limited edition that boasts an ultra-light, hollowed-out 18k gold case fabricated with laser additive manufacturing.

Initial thoughts

The original Monaco from Heuer remains one of the more enduring chronograph designs, with the storied past and distinctive square form. It is refreshing to see TAG Heuer using it as a base for newer, technologically-oriented pieces.

This new limited edition takes the already-supercharged crystallised titanium split-seconds released earlier this year and reimagines the square case. The result is a honeycomb-patterned case that is surprisingly lightweight for the size and material.

The complex and layered construction of the Air 1, here in an exploded view.

The team at TAG Heuer employed a new additive manufacturing technique with the goal of a sturdy yet remarkably light chronograph. Keeping in mind that gold is a dense (thus heavy) metal, making a watch that qualifies as “lightweight” is usually incompatible with including the precious alloy. Here the engineers came up with a way to reduce the volume of gold used, while keeping the components’ sturdiness intact.

The timepiece itself can be a little much in terms of styling, with the very complex case straying away from the classic Monaco format. The textures and tones match well, but the overly layered case its from what could have been a sleeker, more aerodynamic construction. Clearly TAG Heuer is very fond of their motorsport connection, since the overall look and even the name refer to Formula 1.

It is a shame that the new TH-Carbon hairspring was not used in this model, since it would have complemented the overall performance-oriented theme of the Monaco Air 1. As we see TAG Heuer experimenting with exciting new materials, the question remains which techniques will find their way into regular production pieces.

While the metal additive manufacturing method is not cheap and was not used to a great extent in the Monaco Air 1, it is interesting to see what the brand will do in the future. Perhaps the brand will include SLM-crafted pieces inside movements too, since the technique is useful for producing complex and functional shapes.

Selective Laser Melting (SLM)

The fancy-sounding process is one of the more modern manufacturing techniques, falling under the larger umbrella of additive manufacturing (much like 3D-printing). Compared to traditional processes, from rudimentary engine-turning to modern multi-axis CNC machining, additive manufacturing builds a component layer by layer from a base material, instead of removing material out of a block or blank. 

In particular, SLM, also known as laser sintering, is a technique through which a fine metal powder bed is selectively melted by a high-powered laser, then cooled and then heated again in specific patterns, layer by layer, until a complex component is produced. Building something from ground up is sometimes easier for specific meshes and geometries, since traditional machining is constrained by tolerances and the tools’ axis and degrees of freedom. 

How does this relate to the new Monaco Air 1? The complicated case details and lattices are crafted through this avangarde technique, while the base titanium case looks to be manufactured through more basic CNC machining. 

The 5N gold accents are built with a mesh-like structure, reminding of optimised pieces found inside racing cars. Similar titanium meshed accents are found on the lug sides, adding to the intricate ridges of the case.

TAG Heuer is proud of its partnership with Formula 1 and boasts similarities between their new case and the aerodynamic yet strong shapes of F1 car parts. In particular the honeycomb theme is reminiscent of the intricate suspensions on such cars. 

While the textures of the case look quite good — especially with this colour scheme, yet also feels a little too much. The DLC-coated square bezel has asymmetric cutouts which don’t contrast too well with the otherwise symmetric dial. 

The black crown looks slightly undersized, with the two chronograph pushers and gold rattrapante button being noticeably larger than the crown. 

The dial framed by the 41 mm car is generously open-worked, with two distinctive black bridges holding the chronograph hours and minutes registers. A very discreet constant seconds at 6 o’clock helps the piece keep some of the original bi-register look of the Monaco.

The watch weights only 85 g, one gram lighter than the crystallised titanium version released earlier this year. This is quite a feat, giving the complex and layered construction of the case. The hollowed segments built by SLM have certainly something to do with the lightness of the piece. 

A performant engine

Inside the elaborate case can be found caliber TH81-00, TAG Heuer’s top-grade split-seconds chronograph. The movement is derived from the Vaucher cal. 6710 and a structurally-similar caliber is used by Richard Mille.

The caliber includes all the amenities of modern performance chronographs: column wheel operation, a vertical clutch and almost as a bonus a high running frequency of 5 Hz. This allows the mechanism to time elapsed periods to the 1/10th of the second — fitting given its F1 thematic. 

The core structure of cal. TH81-00 is sturdy and reliable, with a free-sprung balance kept secure by a full balance bridge. All in all, this movement holds its candle well against established performance chronograph calibers, like the Rolex 413x models and Omega’s 9900 series. 

The split-second implement is visible on the top of the movement under the automatic winding works. There is a second column wheel controlling the split function, stopping one chronograph second hand while the other ticks on. The rattrapante system looks well-built and straightforward, but lacks the refinement of those found in traditional haute horlogerie movements from the likes of Patek Philippe or Lage.

Another interesting point to make here is that TH81-00 features a fair share of hand-applied finishing. The chequered pattern on the uppermost bridge is scraped by hand and there is sharp bevelled polishing around the balance cut-out. This is more hand-finishing that it’s usually found in these technical-looking pieces. 

Key facts and price

TAG Heuer Monaco Split-Seconds Chronograph Air 1
Ref. CBW218B.FT8124

Diameter: 41 mm
Height: 15.2 mm
Material: Grade 5 titanium and 2N gold
Crystal: Sapphire
Water resistance: 30 m

Movement: TH81-00
Functions: Hours, minutes, seconds, chronograph and split-seconds
Winding: Automatic
Frequency: 36,000 beats per hour (5 Hz)
Power reserve: 65 hours (55 hours with chronograph on)

Strap: Calf leather with embossed  textile pattern and folding clasp

Limited edition: Yes, limited to 30 pieces
Availability: December 2025
Price: CHF150,000

For more, visit Tagheuer.com.