This Fritz Lange-Optik sling psychrometer was part of the military looking East German meteorological set.  I think the set was from the early 1990s, one instrument had a 1989 calibration date.  The thermometers are about 7 inches long.  One is a spirit thermometer and rages from -20C to 40C.  The other is a mercury thermometer and rages from -40C to 40C.
Go to Fritz Lange catalog page.

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