Rare 6×30 Dienstglas marked jxn

Excellent 6×30 binoculars or Dienstglas in very good condition. The Dienstglas is complete with its original leather strap and its leather button retaining flap. The binoculars are nicely marked fxn which indicates production by Helmut Korth, Fabrik fuer Feinmechanik u. Optik, Berlin, this is for me the first time to encounter this manufacturer! Excellent example by an very rare manufacturer in very good condition!