The Rolex Caliber 1165 is a manual-winding mechanical movement developed in the late 1950s to early 1960s, and it is part of Rolex’s 116x subfamily of compact hand-wound calibers. Specifically, the 1165 is a GMT (dual-time) variant of the base Caliber 1160, engineered to include an additional 24-hour hand for tracking a second time zone. While extremely rare and not widely documented in mainstream Rolex catalogs, the 1165 stands out as one of Rolex’s earliest attempts to integrate GMT functionality into a compact, manually wound format.

Technical Specifications

• Type: Manual-wind

• Functions: Hours, minutes, 24-hour GMT hand

• Jewels: 17

• Frequency: 18,000 vibrations per hour (vph)

• Power Reserve: Approximately 42 hours

• Shock Protection: KIF or Incabloc

• Chronometer Certified: No

• Hacking Seconds: No

• Date Function: No

The GMT function was likely implemented via a synchronized 24-hour hand, driven off the main gear train and intended for use with a rotatable 24-hour bezel, which would allow the user to track a second time zone.

Movement Features

Though compact and basic in construction, the Caliber 1165 incorporated several purposeful design traits:

• Three-bridge layout, typical of Rolex’s hand-wound calibers of the era

• Rhodium plating on bridges and plates to prevent corrosion

• Durable mainspring and geartrain, tuned for smooth winding

• Modified gear set to drive the fixed 24-hour hand

• Manual-wind only, with no rotor system

The 1165's 24-hour hand was likely not independently adjustable, meaning it moved in sync with the main hour hand—a design similar to Rolex’s first automatic GMT calibers (like the Caliber 1036).

Watches Powered by Caliber 1165

Due to its rarity, very few watches are definitively known to house the Caliber 1165. Possibilities include:

• Prototype or pre-production GMT watches, possibly produced for internal testing

• Small-cased dual-time travel watches, targeted at niche markets or military applications

• Potential appearance in early Tudor-branded pilot-style watches (though unconfirmed)

These would have featured:

• Rotatable 24-hour bezels or fixed GMT scales

• Compact Oyster-style cases in steel or gold

• Slim profiles due to the manual-wind architecture

• Simple, high-contrast dials optimized for readability

Historical Context

The Caliber 1165 is a mechanical sibling to Rolex’s earliest automatic GMT movements, such as:

• Caliber 1036 – Used in the first GMT-Master Ref. 6542

• Caliber 1065 GMT / 1066 GMT – Experimental or ultra-rare manual-wind GMT versions

It is likely that the 1165 was a limited-run or experimental movement, produced before Rolex committed fully to automatic GMT calibers for commercial use in the GMT-Master line.

Collectibility and Legacy

Due to its scarcity and specialized function, the 1165 is considered:

• Extremely rare, with very few surviving examples (if any) confirmed in circulation

• Of high historical value to Rolex scholars and collectors of early GMT designs

• A transitional movement bridging Rolex’s manual-wind heritage with tool-watch innovation

• A potential museum-grade artifact, if paired with a period-correct case and dial

Final Thoughts

The Rolex Caliber 1165 is one of the brand’s most obscure and fascinating vintage movements. Built during a time of rapid innovation, it represents Rolex’s early exploration of travel-focused complications—specifically GMT tracking—within a manual-wind platform. Though almost unseen today, it remains a symbol of Rolex’s drive to experiment with useful mechanical functions across all case sizes and categories. For collectors and historians, the 1165 is a mechanical whisper from Rolex’s formative years in tool-watch development.