Introduced in 1969, the Heuer Monaco was among the most revolutionary chronographs of its era. Its unconventional square case, striking blue dial and pioneering automatic chronograph movement represented a bold departure from traditional watchmaking. Developed during a period of intense competition to create the first automatic chronograph movements, the Monaco became an enduring symbol of late 1960s design and Heuer's close association with motorsport.

The earliest examples featured a metallic blue dial bearing the name “Chronomatic”, a designation soon abandoned in favour of the more easily understood “Automatic Chronograph”. The watches produced during this brief transition retained the distinctive metallic finish and rectangular steel hands of the original Chronomatic models, while introducing the dial configuration that would become standard on subsequent Monacos.

Known among collectors as the “Transitional” Monaco, these early examples represent a particularly sought-after chapter in the model's history, preceding the more familiar production version famously worn by Steve McQueen in the 1971 film Le Mans.

According to Heuer researcher Richard Crosthwaite, examples of the earliest Chronomatic and Transitional Monaco models have been documented within the serial number range 157189–157589, with the majority recorded below 157400. Crosthwaite further estimates that fewer than 700 examples of the Transitional 1133B were produced, highlighting the rarity of this early execution.

The present example displays the characteristic metallic blue dial, rectangular steel hands and early dial configuration associated with the Transitional series. Its notably low serial number, 157358, places the case within the documented range of the earliest Monaco examples, adding to its historical and collector interest.

Accompanied by a Heuer presentation box, leather strap and an unfilled certificate.