Two balances that agree with each other
By Marco Bellini, Zurich ยท
Put two balance wheels close together and, under the right conditions, they start to beat in step. Breguet and others tried it in clocks. Doing it in a wristwatch, where every movement of the arm disturbs both oscillators, is another matter. Armin Strom's answer is a thin patented spring that couples the two balances, and the company says they lock into resonance within minutes.
The ARF21 is hand-wound, 48 hours, and the two balances sit on the left side of the dial where you can watch them. The time is on a blue sub-dial on the right. Steel case, 41 mm by 11.6 mm. Bridges are finished by hand, and properly.
The difficulty is value. This Manufacture Edition is limited to 50 pieces and costs $89,000. Any gain in rate stability is real but hard for an owner to notice, so you are paying mainly for the engineering and for watching it work.
If that is what you want, few watches show it as clearly. I would choose it over most tourbillons at the same price, because the idea is better.