The Jaeger-LeCoultre Master Calendar (Reference 147.8.41.S) is a sophisticated automatic timepiece characterized by its comprehensive "triple calendar" and moonphase complications. Produced primarily between 2005 and 2013, this model is often referred to by its commercial reference Q151842A.

• Case: 40mm stainless steel with a polished finish and concave lugs. Some secondary listings cite 39mm or 40.5mm, but 40mm is the manufacturer standard for this reference.

• Movement: JLC in-house Calibre 924, an automatic self-winding movement with 41 jewels and a 22k gold-edged rotor.

• Dial: Sunray-brushed or matte silver dial featuring:

  • Day and Month: Displayed in apertures near 9 and 3 o'clock respectively.

  • Date: Indicated by a central pointer hand tipped with a red crescent moon.

  • Moonphase & Seconds: Integrated subdial at 6 o'clock.

  • Power Reserve: Fan-shaped indicator located at 12 o'clock.

• Power Reserve: Approximately 40 to 45 hours.

• Case Back: Transparent exhibition sapphire crystal allowing a view of the movement.

• Water Resistance: Rated to 5 ATM (50 meters).