====== Patek Philippe Annual Calendar 5350 ======

{{wst>image_cr|Patek Philippe|Annual Calendar 5350}}

[[Patek Philippe]]'s [[2006]] **Annual Calendar Ref. 5350** was one of the first wristwatches with a [[silicon]] [[balance spring]] ever produced. It is the second member of their [[Patek Philippe Advanced Research|Advanced Research]] project.

===== Overview =====
In the 2000s, Patek Philippe set up an [[Patek Philippe Advanced Research|Advanced Research]] project to address the long-standing issues of [[isochronism]] and durability in watches. The main technology applied to this task was a proprietary alloy of [[silicon]] known as "[[Silinvar]]". The company proceeded steadily, producing first a Silinvar [[escape wheel]], then a [[hairspring]], an [[anchor]], and a [[balance]].

**Ref. 5350** was the second Advanced Research watch, introduced in [[2006]]. [[PP 324|Cal. 324 S IRM QA LU]] included the Silinvar escape wheel of its predecessor and added a flat Silinvar hairspring to the mix. This made it one of the first watches ever produced with such a spring. The [[display caseback]] includes a large "[[cyclops]]" magnifier to allow the owner to inspect these two high-technology components.

Although it used these high-tech components, Ref. 5350 was nevertheless a Patek Philippe. It included their revolutionary [[annual calendar]] mechanism with day and month subdials inset at 10 00 and 2 00, a date window below the [[moon phase indicator]] at 6 00, and a simple "+/-" [[power reserve indicator]] at 12 00. The dial features Arabic numerals at 3, 9, and 12, applied markers at all other hours but 6, and a "railroad" seconds track. The hour and minute hands are leaf shaped and feature [[lume]]. It has a traditional Patek Philippe [[pink gold]] case, with long integrated lugs.


<WRAP ud ud_mod>

**Reference:**
  * 5350 pink gold, 300 produced

**Movement:**
  * [[Automatic]] [[manufacture]] movement [[PP 324|Caliber 324 S IRM QA LU]], 28,800 A/h
  * [[Annual calendar]] module
  * [[Silinvar]] [[escape wheel]] with Silinvar [[Spiromax]] [[balance spring]]
  * [[Geneva Seal]]

**Case:**
  * [[Pink gold]]
  * D 39 mm, H 11.7 mm
  * [[Sapphire crystal]] caseback with magnifying bubble

**Dial:**
  * Silver

**Functions:**
  * Hours, minutes, [[central seconds]]
  * [[Annual calendar]] with day, date, month
  * [[Moon phase indicator]]

**Limited edition:**
  * 300 pieces
  * Predecessor [[Patek Philippe Annual Calendar 5250]]
  * Successor [[Patek Philippe Annual Calendar 5450]]
</WRAP>

{{tag>Watch_models Watches_with_annual_calendar Patek_Philippe_models Patek_Philippe_references Patek_Philippe_Advanced_Research_models}}