u muct go for center second for beohbachtung!
Yenfoolun,
What is beohbachtung? 
The Beobachtungs-Uhren ("B-Uhr", observers watch) were made for the WWII Luftwaffe. These large watches contained high-quality pocket-watch movements for use in aircraft navigation. They were attached to the arm with long leather straps that fit around the outside of the flying clothing.
There were five manufacturers: A. Lange & Söhne, IWC, Laco, Stowa, and Wempe. Features that the watches have in common:
* Cases 55 mm in diameter, marked "FL 23883"
* Large crowns for use with gloves
* Indirect center seconds
* Stop ("hack") seconds
* Breguet balance springs
* No shock protection
1. A. Lange & Söhne (Glashütte)
Movement: Cal. 48/1
The movement has a large (20 mm) balance and 17 jewels set in chatons, and often uses a swan-neck regulator. Because of the size of the order, the watches were assembled by a number of firms, including Huber (Munich), Felsing (Berlin), Schieron (Stuttgart), Suchätzle und Tschudin (Pforzheim), and Wempe (Hamburg).
2. IWC (Schaffhausen)
Movement: Cal. 52 SC
A total of 1200 cal. 52 SC (offically "52T-19''' H6 S.C.") movements were made, and around 1000 went into the B-Uhr made by IWC. The cal. 52 SC was 43.15 mm (19 lignes) x 6.0 mm, 16 jewels, and 18,000 bph. The movement bore a swan-neck regulator and were adjusted in 6 positions and tested at the Gesundbrunnen observatory in Glashütte. The 55 x 16.5 mm cases were numbered 1033201 to 1034200 and had an additional anti-magnetic inner case.
3. aco (Lacher & Co., Pforzheim)
Movement: Durowe cal. D5
Durowe (Deutsche Uhren-Rohwerk) was part of Laco. The 22-ligne, 22-jewel movement has a very large (22 mm) balance and a simple regulator.
4. Stowa (Walter Storz, Pforzheim)
Movement: Unitas (Tramelan) cal. 2812
The 18-ligne, 20-jewel movement has a swan-neck regulator and is nickel-plated with Geneva stripes.
5.Wempe (Hamburg)
Movement: Thommen (Waldenburg) cal. 31
The movement has a snail-cam fine regulator.
