This Windmesser or Anemometer Air-speed Indicator or ASI was manufactured by Wilhelm Morell in Leipzig with a scale of 0-25 which corresponds to a maximum airspeed of 250 KPH or 155 MPH.  This particular example has a serial number of 121329.  The glass is stamped with a semi-transparent inspector's stamp of the Fliegertruppen symbol of a winged propellor and "P.u.M." The photo below shows an anemometer like this one attached to the starboard interplane strut of an Albatros D.Va of Jasta 16b.  Note that this object does not have a cage around the cups and one cup has been reattached; it is in rough condition.