Rolex’s Next Big Innovation: The Ecobrass Balance Wheel

Rolex only implements new technology when it offers a clear advantage. The brand takes an incremental approach, refining materials and movements only when there’s an undeniable benefit. This is why advancements like the Parachrom hairspring and Chronergy escapement became permanent fixtures in Rolex’s catalog—they enhanced performance without any real drawbacks. (Yes, the sapphire crystal and ceramic bezel are more debatable.)

In September of 2022, Rolex filed a patent suggesting its next movement evolution: Ecobrass balance wheels. This material change significantly improves magnetic resistance without requiring a complete movement overhaul, making it a logical next step for Rolex’s watchmaking.

If implemented, this could bring Rolex’s entire lineup to new levels of durability against magnetism. The question is, which model will get it first?

What Is An Ecobrass Balance Wheel?

Text in image translated from French. Original Image Source: database.ipi.ch

The balance wheel is one of the most critical components in a mechanical watch. It oscillates back and forth, regulated by the hairspring, to ensure precise timekeeping. Rolex currently uses copper-beryllium (CuBe) alloy for its balance wheels, a material that has served well but isn’t optimized for extreme magnetic fields.

Ecobrass—a lead-free brass alloy (CuZn21Si3P)—offers significantly higher electrical resistivity than CuBe. Rolex’s patent suggests this change could increase magnetic resistance by 60% or more, pushing the movement’s threshold beyond 35,000 gauss in testing (more than double METAS’ threshold).

Tudor METAS Testing Facility. Image Source: Hodinkee

The reason? Eddy currents. When a watch enters a magnetic field, small loops of electricity form within the movement which can disrupt the balance wheel’s oscillation. Ecobrass minimizes these currents.

Rolex’s History with Anti-Magnetism

Milgauss internal cage. Image Source: Luxury Bazaar

Rolex has tackled magnetic resistance for decades. The Milgauss, first introduced in 1956, relied on an internal cage—a soft iron shield surrounding the movement—to block magnetic interference. This was effective but added bulk and wasn’t scalable across the Rolex lineup.

A major shift came in 2000 with the introduction of the Parachrom hairspring, which was highly resistant to magnetism and became standard across Rolex movements. In 2015, the Chronergy escapement followed, further improving efficiency (its primary appeal) while helping mitigate magnetic effects.

Blue Parachrom Hairspring. Image Source: Perpetual Passion

Ecobrass takes things a step further. Instead of shielding the movement, Rolex is now engineering its components to ignore magnetism entirely. This approach aligns with the broader industry trend seen in Tudor and Omega’s Master Chronometer-certified movements, which use non-magnetic materials to eliminate interference at the source.

Will Ecobrass Debut in a New Milgauss?

If Rolex wants to showcase its next-generation magnetic resistance, reintroducing the Milgauss with an Ecobrass balance wheel would be the obvious move.

Since the Milgauss was discontinued in 2023, people have wondered what a comeback could look like. Regardless of what a new Milgauss would look like on the outside, Ecobrass would be a compelling marketing story. Rolex could frame the new Milgauss as more than just a model comeback—it would be a revival of Rolex’s innovation in antimagnetism.

Or Will Rolex Introduce It Quietly?

Image Source: Revolution Watch

Historically, Rolex rolls out movement upgrades gradually. The Parachrom hairspring first appeared in the Daytona before expanding across the catalog. The Chronergy escapement debuted in the Day-Date’s Caliber 3255 before making its way into other models.

Ecobrass could follow the same playbook, appearing first in a new-generation Caliber 32XX movement—potentially in the Day-Date or Datejust—before reaching sports models.

That said, the Milgauss remains the most logical first candidate. It’s Rolex’s flagship anti-magnetic model, and what better way to bring it back than with an industry-leading movement upgrade?

Final Thoughts

Image Source: WatchPro

The Ecobrass balance wheel patent is another step in Rolex’s long-term strategy of incremental but meaningful improvements. Unlike some past advancements that sparked debate, this one has no real downside—it enhances performance without altering the movement’s architecture or adding bulk.

A next-generation Milgauss seems like the most compelling launch vehicle, but Rolex could take a quieter route by introducing Ecobrass in a new 32XX movement before expanding its use. Either way, this is one of the most significant Rolex movement advancements in years—one that will likely define the next generation of Rolex watches.