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Movement tier: unclassified · caliber Ulysse Nardin Cal. UN-250: in-house automatic carousel with silicon escapement, 28,800bph, 60h PR; used in Freak Vision latest; silicon oscillator replaces hairspring+balance · 60h power reserve (2.5 days) · family design Ludwig Oechslin
Large case: suits wrists 7 in+ (18 cm+)
45 mm case. A bold, statement-size wear. Best suited to larger wrists where the case sits flush.

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Authentication

Cal. UN-250 latest Freak generation; reference number on caseback distinguishes from UN-230 variant.

Known issues in the market
  • Time set and winding performed through caseback mechanism, not a conventional crown; any Freak Vision with a conventional side crown is wrong.
  • Reference number on caseback confirms correct generation; verify against listing description.
AreaWhat to checkWhat is correctRed flag
casebackCal. UN-250 designation and reference numberCal. UN-250 on caseback; reference number matches UN-250 generation specificationUN-230 caseback on claimed UN-250; reference number mismatch; wrong generation
crownAbsence of conventional side crownNo conventional side crown; time set and winding via caseback mechanism onlyConventional side crown present; wrong case generation
movementSilicon carousel componentsSilicon escapement components in carousel visible through crystal; smooth carousel rotationNon-silicon escapement; incorrect carousel architecture
Common legitimate replacements
  • Strap; UN OEM rubber.
  • Crystal; Freak-specific curved sapphire.
Expert resources: Ulysse Nardin Freak Vision (UN-250) press materials and technical documentation.

Authentication guide

Last reviewed June 2026

The latest Freak Vision generation uses Cal. UN-250 in titanium, with a silicon oscillator that replaces the conventional hairspring and balance wheel entirely. No hands, no dial, no crown. Same fundamental authentication logic as the earlier Vision applies, with the silicon oscillator as the additional tell.

Known reproduction risks

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HIGH RISK

Any Freak with conventional hands is not a Freak. The silicon oscillator and no-crown design are the specific tells for this generation.

  • Conventional hour or minute hands -- automatic disqualifier
  • Crown on the case -- immediate disqualifier
  • Conventional metallic balance and hairspring in the movement instead of the silicon oscillator
  • Metal case instead of titanium for this specific reference

The UN-250 silicon oscillator is the one component that cannot be replicated by any factory outside of UN's development partnership with the oscillator manufacturer. Its presence or absence is definitive.

Dial variants by era

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EraDescriptionIdentifiers
Current generation (Cal. UN-250)Titanium case, 45mm. Silicon oscillator replaces the traditional hairspring and balance. The movement carousel rotates to indicate time against the chapter ring inside the crystal.
  • No dial, no hands -- movement rotates inside the case as the time display
  • No crown -- winding and setting via rotating caseback
  • Titanium case with characteristic grey-matte finish
  • Silicon oscillator (flat silicon spring replacing the conventional balance) visible in the carousel
  • Chapter ring on the crystal interior for time reading

Service part flags

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Silicon oscillator

Original: Cal. UN-250's defining component: a flat silicon spiral spring that replaces the hairspring and balance wheel. It appears as a flat, dark, non-reflective element in the movement. It is proprietary to UN and not available from aftermarket sources.

Replacement tells
  • Conventional metallic hairspring and balance wheel in place of the silicon oscillator
  • Any component that reflects light as polished metal where the flat silicon element should be visible
Caseback winding mechanism

Original: The rotating caseback winds the mainspring and sets the time. It should turn with consistent resistance in the winding direction and a different resistance in the time-setting direction.

Replacement tells
  • Caseback that spins freely without winding resistance
  • Any crown added to the case band -- there is no crown on a genuine Freak Vision
  • Caseback rotation with no distinction between the winding and setting directions

Case back markings

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Current generation
  • Rotating caseback with directional indicators for winding and setting
  • "Ulysse Nardin" and "Freak Vision" on the caseback or case band
  • Reference 2505-250LE and serial number on the case band
  • Titanium hallmark appropriate to the case material

Movement tells

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  • Cal. UN-250 eliminates the conventional balance by using a silicon oscillator. The timekeeping rate depends on the oscillator's spring geometry; any rate check after service should be done at an authorized UN center.
  • Power reserve is approximately 60 hours. Functional test: wind fully via the caseback and confirm the carousel rotates continuously for at least 50 hours.
  • Silicon oscillator requires no lubrication. Service documentation mentioning lubrication of the oscillator indicates incorrect service procedure.
  • The carousel rotation should be smooth and continuous. Any step or jitter in the rotation under observation indicates an issue with the escapement or oscillator interaction.
Sources: Ulysse Nardin -- Freak Vision UN-250 caliber specification; WatchPro -- Freak Vision latest generation technical review.

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