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Armin Strom
Armin Strom System 78 Gravity Equal Force Black ST19-GEF.90

Armin Strom System 78 Gravity Equal Force Black

SKU: ST19-GEF.90 

Armin Strom
  • $21,000.00
  • $1,000.00

This item requires a deposit to pre-order. A separate invoice will be sent to you for the balance when we are ready to ship the item.

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The world’s first automatic watch with constant force transmission

The Armin Strom Gravity Equal Force is the world’s first automatic watch with constant force transmission. The result is consistent power delivery to the balance which ensures that the watch always delivers flawlessly constant precision.

A key innovation, exclusive to the first set of System 78 watches, is the very first implementation of a “stop-work” declutch mechanism to be deployed in combination with an automatic movement. Typically seen only in haute-horology timepieces that are orders of magnitude more expensive, a “stop work” mechanism offers the benefit of more consistent energy transmission. To fully understand the benefit of this mechanism, one must first understand why an ordinary watch will not run at a consistent rate throughout the duration of its power reserve. The problem begins with the mainspring that inhabits every mechanical timepiece. A mainspring is a tightly coiled metal ribbon that resides inside of a watch’s barrel to deliver force to the movement. However, the force that a mainspring will deliver in an ordinary watch as it unwinds can never be delivered consistently, because the force provided will necessarily be higher when fully wound than it will be towards the end of its power reserve. To address this, Armin Strom implemented a “stop work” mechanism in the Gravity Equal Force that limits the mainspring from fully unwinding and thereby leverages only that part of the mainspring’s unwinding process which can deliver power most consistently.



  • Stop-Work declutch mechanism and Equal Force Barrel


    • Winding-mechanism: Automatic with micro rotor turning on dial side
    • Regulating system: Screwed balance with steel spiral
    • Frequency: 25.200 vph / 3,5 Hz
    • Number of jewels: 28
    • Power reserve: 72 hours


    • Stainless steel
    • Sapphire crystal and case back with anti-reflective treatment
    • Diameter: 41.00 mm
    • Height: 12.65 mm
    • Lug-to-Lug: 48.09 mm
    • Water-resistance: 30 m


    • Offset with running seconds subdial


    • Steel with hand finishing and Super-LumiNova® filling


    • Delivered with a black fabric strap with light grey stitching
    • Width lugs/buckle: 20/18 mm


    • Folding clasp in stainless steel