For the 10th edition of the biennial Duchenne muscular dystrophy Only Watch charity auction, independent watchmaker Armin Strom has donated a unique piece for the fifth time.

The Only Watch 2023 Armin Strom Gravity Equal Force “Ultimate Sapphire” timepiece features a transparent green sapphire off-center dial, contrasted by a printed red logo, with a yellow minute track and hour markers.

While the watch itself does not have anything new horologically, the watch possesses the world’s first automatic caliber with a constant force transmission. Armin Strom’s Gravity Equal Force invention uses a stop declutch mechanism and a Maltese cross, a technical solution normally found in hand-wound pocket watches, with an automatic winding system.

Essentially, a Maltese cross inside the barrel controls the mainspring and stops it from fully unwinding. Armin Strom’s Maltese cross is, however unique in that it’s also declutched when the rotor has given the mainspring its optimum tension. By cutting the top and the bottom parts of the power reserve, a constant force is delivered with an extremely secure, stable, and precise amplitude and isochronism throughout the entire cycle.

With the Armin Strom development, accuracy is consistent throughout all 72 hours of power reserve, which is shown on a discreet indicator on the Equal Force barrel itself.

Additionally, the watch features dark gray ruthenium components and hand-applied decorations such as polished bevels, black polishing, polished sinks, perlage, Geneva stripes, and various grainings. The black movement plate is hand-guillochéd by Kari Voutilainen’s atelier.