Adolphe Sax first learned about valved brass instruments in his father's workshop in Brussels. Charles-Joseph Sax, who took an early interest in the development of valves, preferred the German designs. This orchestral horn, which survives with one crook for the key of F, has two Stoelzel valves. Named after its inventor, Heinrich Stoelzel (1777-1844), this valve type was popular in France, as well as in Germany. Although the two valves are not sufficient to play a fully chromatic scale, players could still do so by simultaneously placing their right hand inside the bell to further modify the pitches.