This is a list of manufacturers of horns. Not all still exist today. The horn is a brass instrument that consists of tubing wrapped into a coiled form, now with finger-operated valves to help control the pitch but originally without valves to control the pitch. ...
The Mozart Horn Concerti, for example, were written for this type of horn, called the natural horn in the modern literature.
Around 1815, the horn took on a new form, as valves were introduced, which allowed the player to switch between crooks without the effort of manually removing one from the horn and inserting a new one.
The relative merits of F versus B-flat were a hotbed of debate between horn players of the late nineteenth century, until the German hornmaker Kruspe produced a prototype of the "double horn" in 1897.