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Top-tier supplier movement · caliber ETA/Valjoux 7750: Swiss automatic chronograph, 28,800bph, 42h PR, 25j; cam-and-lever system (column-wheel optional), workhorse chronograph ebauche · 42h power reserve

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Medium-large: suits wrists 6.5 in+ (16.5 cm+)
41 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

Matte case surface is operational; any polished EZM 13 has been incorrectly serviced.

Known issues in the market
  • The EZM matte surface minimizes light reflection; polishing removes this functional property.
  • Cal. 7750 cam-actuated architecture is appropriate at this tier; column-wheel is not required.
AreaWhat to checkWhat is correctRed flag
caseMatte surface integrityUniform matte case surface with no polished sections; light-reflection minimization intactPolished sections on case; mirror finish on any case surface; incorrect case finishing
casebackValjoux 7750 caliberETA/Valjoux 7750 cam-actuated chronograph architecture; Sinn serial number presentNon-7750 movement; incorrect caliber; serial inconsistent with EZM 13 production
crystalAR coatingAnti-reflective coated crystal on both sides; minimal reflectionLost AR coating; strong reflections; scratched crystal
Common legitimate replacements
  • Original Sinn strap or bracelet; factory replacement options through Sinn.
Expert resources: Sinn EZM 13 product documentation at sinn.de. ETA Valjoux 7750 technical documentation.

Authentication guide

Last reviewed June 2026

The EZM 13 is Sinn's mission-timer chronograph, rated to 500M, with a Valjoux 7750-based movement and TEGIMENT case. It is a professional tool watch with specific dial layout and bezel configuration. Replica exposure is minimal.

Known reproduction risks

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LOW

The EZM 13 is a niche professional chronograph with very low replica exposure. The risk profile is primarily non-TEGIMENT substitution or non-locking pusher replacements.

  • Pushers that do not screw in for depth protection
  • Missing "TEGIMENT" caseback engraving
  • Sub-dial layout inconsistent with Valjoux 7750 configuration

Dial variants by era

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EraDescriptionIdentifiers
2008 to presentMatte black dial with three chronograph sub-dials (Valjoux 7750 layout: 30-minute at 12, 12-hour at 6, running seconds at 9). Large luminous Arabic numerals. Unidirectional rotating bezel.
  • "EZM 13" text on the dial identifying the reference
  • Three sub-dial registers in the Valjoux 7750 configuration: 30-minute at 12, running seconds at 9, 12-hour at 6
  • Large luminous Arabic numerals with broad hands
  • "500M" water resistance notation on the dial
  • Unidirectional rotating bezel with timing scale
  • Pushers at 2 and 4 o'clock for start/stop and reset

Service part flags

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Chronograph pushers

Original: Round pushers at 2 and 4 o'clock with screw-in protection for 500M water resistance. The pushers should screw in flush before submersion and are functional in the unscrewed position. Pusher actuation on the Valjoux 7750 is a cam-lever mechanism with a firm but not column-wheel-precise feel.

Replacement tells
  • Pushers that do not screw in -- the EZM 13 uses locking pushers for depth rating; any pusher without thread engagement is non-original or damaged
  • Pusher actuation with inconsistent resistance around the pusher travel range
  • Pusher diameter or height inconsistent with the case pusher tube profile
TEGIMENT case

Original: TEGIMENT surface hardening on the 41mm case. "TEGIMENT" is engraved on the caseback. The case resists scratching better than standard steel.

Replacement tells
  • Caseback without "TEGIMENT" engraving on a stated EZM 13
  • Case surface that is easily scratched by a coin or key -- TEGIMENT steel is measurably harder
Sub-dial layout

Original: The Valjoux 7750 layout places the 30-minute register at 12, running seconds at 9, and 12-hour register at 6. This is the standard 7750 configuration. Any deviation from this layout indicates a movement swap.

Replacement tells
  • Sub-dial positions inconsistent with the Valjoux 7750 layout (e.g., running seconds at 6 indicates a non-7750 movement)
  • Sub-dials with incorrect scale range (e.g., a 60-minute register rather than 30-minute at 12)

Case back markings

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2008 to present
  • "SINN SPEZIALUHREN" and "GERMANY"
  • "TEGIMENT" engraved on caseback
  • "EZM 13" reference identification
  • "500M" water resistance rating
  • Argon dehumidification notation on some variants
  • Serial number on caseback or case band

Movement tells

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  • Valjoux 7750 beats at 28,800bph with a 42-hour power reserve. A fully wound EZM 13 that stops before 36 hours warrants service.
  • The 7750 is a widely serviced ebauche with abundant parts. Sinn modifications (finishing, signing) are applied over the base caliber. The movement is not proprietary Sinn architecture.
  • The date change at midnight should be rapid and crisp. Day/date variants should show both advancing together. Slow or two-stage date advance indicates worn quickset.
  • Chronograph reset should return all hands to zero in a single action with no creep or partial reset. Any sub-dial hand that does not return to zero exactly indicates a worn or damaged heart cam.
Sources: Sinn -- EZM 13 technical specification; WatchUSeek -- Sinn professional chronograph forum.

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