A nice original WWI German miniature Honour Cross of the World War 1914/1918 (aka Hindenburg Cross) for combatants, mounted with ribbon on a buttonhole device. This would have been worn on the lapel. 
 
The Honour Cross of the World War 1914/1918 (German: Das Ehrenkreuz des Weltkrieges 1914/1918), commonly known as the "Hindenburg Cross" or the German WWI Service Cross was established by Field Marshal Paul von Hindenburg, President of the German Weimar Republic, by an order dated 13 July 1934, to commemorate service of the German people during the First World War. This was Germany's first official service medal for soldiers of Imperial Germany who had taken part in the war, and where they had since died it was also awarded to their surviving next-of-kin. Shortly after its issuance, the government of Nazi Germany declared the award as the only official service decoration of the First World War and further forbade the continued wearing of German Free Corps awards on any military or paramilitary uniform of a state or Nazi Party organization.