====== Sinn 903 ======
{{wst>image_r|Sinn_903_St|Sinn 903 St}}
{{wst>image_r|Sinn_903_St_Schwarz|Sinn 903 St Black}}
{{wst>image_r|Sinn_903_St_Silber|Sinn 903 St Silver}}
**Ref. 903** is a [[chronograph]] watch from [[Sinn]].

===== Overview =====
Sinn refers to this as their "Navigation Chronograph" model, and it features traditional aircraft markings on an internal rotating [[bezel]]. The 903 Classic and H4 use the [[hand winding]] [[Lemania 1883]] movement with four [[subdial]]s including [[moon phase indicator]], while the rest use an [[automatic]] [[Sellita]] [[SW 510]] movement with subdials at 3, 6, and 9. All feature an extra crown on the left side of the case to turn the inner bezel, though this is at 10 00 in the SW 510 models and 8 00 for Lemania versions.

All versions feature a 41 mm case with traditional "twisted" lugs. The case is 13.2 mm thick for Lemania-based models and 14.5 mm thick for SW 510 models. All feature [[sapphire]] crystal on the front and [[display caseback]].

===== References =====
  * Sinn 903 Classic (2009) - [[Lemania 1883]] movement, moon phase indicator and date by pointer at 12 00, black dial, cream bezel, limited edition of 300 examples
  * Sinn 903 H2 (2006-2007) - [[Lemania 1872]]
  * Sinn 903 H4 (2006-2012) - [[Lemania 1883]] movement, moon phase indicator and date by pointer at 12 00, anthracite dial, black bezel
  * Sinn 903 Pl Hd 12 (-2001) - [[Lemania 1873]]
  * Sinn 903 Pl Hd 24 (-2001) - [[Lemania 1877]]
  * Sinn 903 St (2005-present) - [[SW 510]] movement, black dial, cream bezel and subdials
  * Sinn 903 St Aut (-2004) - [[Valjoux 7750]]
  * Sinn 903 St Black (2004-2015) - [[SW 510]] movement, black dial, subdials, and bezel
  * Sinn 903 St B E (2015-present) - [[SW 510]] movement, blue dial, cream bezel and subdials
  * Sinn 903 St Hd 12 (-2001) - [[Lemania 1873]]
  * Sinn 903 St Hd 24 (-2001) - [[Lemania 1877]]
  * Sinn 903 St HUMMER (2004) - [[Valjoux 7750]]
  * Sinn 903 St Silver (2004-present) - [[SW 510]] movement, silver dial, bezel, and subdials


<WRAP ud ud_mod>

**Movement:**
  * Mechanical [[chronograph]] movement [[Lemania 1883]] or [[SW 510]], 21,600 or 28,800 A/h
  * 17 or 26 [[jewels]]
  * [[Hand winding]] or [[automatic]]

**Case:**
  * [[Stainless steel]], DIN material number 1.4435, polished/[[satin-finished]]
  * D 41 mm, H 14.5 mm
  * [[Sapphire crystal]] and [[sapphire crystal]] caseback, with [[anti-glare treatment]] on both sides
  * Integrated rotating bezel with logarithmic scale
  * [[Screw-in crown]]
  * [[Waterproof]] to 100 m, low pressure resistant

**Functions:**
  * Hours, minutes, [[small seconds]]
  * Date at 4 30 or by pointer at 12 00
  * [[Chronograph]] 12 hours counter, 30 minutes counter, 60 seconds counter
  * [[Slide rule]] function

**Bracelet: **
  * Leather strap or steel bracelet
</WRAP>

{{tag>Watch_models Chronographs Sinn_Pilot's_Watch_models Sinn_Instrument_Chronograph_models}}