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The Encyclopedia of Horology

Wristwatch · Chronograph

Omega Speedmaster Mark 4.5 Professional

Partially verified

The Omega Speedmaster Mark 4.5 Professional, reference 176.0012, is an automatic chronograph wristwatch introduced during the mid-1970s. It features a 42mm stainless steel tonneau-shaped case with hooded lugs and radial brushing. The dial follows a "TV-style" layout with squared-off registers, protected by a hesalite crystal. The watch is powered by the Omega Caliber 1045, an automatic movement derived from Lemania architecture, which includes central chronograph seconds and minute counters, along with a day-date display. The piece is fitted with a stainless steel bracelet and was designed for daily wear with a 48-hour power reserve and 30m water resistance. This model serves as part of the broader Mark series, representing a shift in Omega's design language during the period of its production.

Front view of the Omega Speedmaster Mark 4.5 Professional showing the dial and bracelet.
Front view of the Omega Speedmaster Mark 4.5 Professional showing the dial and bracelet. — Analog Shift. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
shop.analogshift.com
Category
Wristwatch · Chronograph
Maker / attribution
Omega
Reference
176.0012
Catalogue / lot identifier
Source URL identifies the listing
Source-reported date
mid-1970s
Source-reported place
Not established

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Case and Dial Design

The Mark 4.5 is characterized by a 42mm stainless steel tonneau case, which features hooded lugs and a radial brushing finish. The architecture of the case is described as cushion-shaped and solid. The dial is distinguished by a 'TV-style' layout, which involves the squaring off of the chronograph registers to manage visual balance while maintaining legibility.

The dial is shielded by a hesalite crystal, which is the manufacturer's trade term for its specific acrylic material. The overall design language is noted for its utility and presence, intended to function within the context of the 1970s, featuring a solid caseback and being paired with a steel bracelet.

Evidence for this section
  • “The 42mm stainless steel tonneau case, with hooded lugs and sweeping radial brushing, continues the muscular design language first explored with the Mark II.”
  • “The dial adopts the distinctive “TV-style” layout, squaring off the registers and tightening the visual balance”
  • “30m water resistance, solid caseback, steel bracelet—this was a Speedmaster designed for the realities of the 1970s”

Movement and Functionality

The watch utilizes the Omega Caliber 1045, an automatic movement developed from Lemania chronograph architecture. This movement is specifically noted for its inclusion of both a central chronograph seconds hand and a central chronograph minute counter, which are intended to improve the readability of elapsed time measurements.

Beyond the chronograph functions, the Caliber 1045 provides a day-date display. The movement is specified as having a 48-hour power reserve, contributing to the utilitarian design goals of the watch during its production period.

Evidence for this section
  • “Powering it is Omega’s automatic Caliber 1045, derived from Lemania’s celebrated chronograph architecture.”
  • “A central chronograph seconds hand is paired with the highly practical central chronograph minute counter”
  • “Automatic, 48-hour reserve, 30m water resistance”

Historical Context and Series

Part of the Omega Mark series, the 176.0012 is positioned as an experimental model within the brand's larger chronograph lineage. It was produced for a short window starting in the mid-1970s, acting as an alternative to the traditional Speedmaster "Moonwatch" design.

The source describes this watch as an example of Omega's effort to update its chronograph design for the decade, moving away from previous iterations to create a more technical and modern aesthetic for the era.

Evidence for this section
  • “Introduced in the mid-1970s and produced for only a short window”
  • “Within the Mark lineage, the Mark 4.5 represents the Speedmaster at its most experimental.”
  • “Omega’s ongoing effort to rethink its most famous chronograph for a new decade.”

Open research questions

  • What is the specific material composition of the inner tachymeter ring seen in the photos?
  • Does the movement contain any unique hallmarks beyond the Caliber 1045 designation?

Source evidence

Recorded claims and source quotations for Omega Speedmaster Mark 4.5 Professional
FieldSource-reported valueSource quotation
MakerOmega“Vendor: Omega”
Reference176.0012“ref. 176.0012 Speedmaster Mark 4.5”
Case dimensions42mm“42mm stainless steel tonneau case”
MovementCaliber 1045“Powering it is Omega’s automatic Caliber 1045”
Crystal materialHesalite“'hesalite' (Omega’s trade name for a type of acrylic crystal)”
Water resistance30m“30m water resistance”
Date of introductionmid-1970s“Introduced in the mid-1970s”

Visible details

  • Tonneau-shaped case with radial brushing
  • Hesalite crystal over the dial
  • Integrated stainless steel bracelet
  • Day-date window located at the 3 o'clock position

Research qualifications

  • The specific production window is described only as a 'short window'
  • The exact material composition of the gold-colored inner bezel ring is not detailed

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

ساعت مچی امگا Omega Speedmaster Mark 4.5 Professional رفرنس 176.0012

Reviewed 2026-11-02 · Record 29138173ce

Terms in this record

Glossary explanations for terms named in this object’s record.

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