Rate of Climb / Vertical Speed Indicator, 5 M/S, Luftwaffe Variometer

Here is an early WWII-era Vertical Speed Indicator used in aircraft of the German Luftwaffe, measuring vertical speed in a climb or descent from - 5 meters/second to + 5 meters/second. It appears to be Fl.22379, although it is not marked with an Fl number.  It has a manufacturing date of November 1938.

Measures ~3.25 inches diameter and ~2.5 inches deep. It is in reasonable condition given its age.