Firma Ed. Kruspe was granted utility model D.R.G.M. 964253 on September 9, 1926 for the horn shown above. It is a modification of the Gumpert-Kruspe compensating double horn (D.R.G.M. 295125, 1906) to which was added a valve "for stopping without transposing or replacing tubing." 

 
Announcement in Zeitscrhift für Instrumentenbau, January 1, 1927, p.307