Double horn. Nominal pitch: F+B♭.

Technical description: 1st, 2nd and 3rd valves compensating with respect to 4th; stands in F, 4th valve gives B♭. The 4th valve is a 'registre' with a very long rotor with its axis parallel to the windway through valve 1-3; when operated, it adds additional tubing to the valve loops of the three main valves. The compensating loops of the first and third valves have their own tuning-slides, but there are no tuning-slides for the second valve on either side because of shortness of passages. Metal construction: yellow brass with german silver mouthpipe sheath, stay plates, finger hook, valve caps, levers and touchpieces. Seamless tubing. Bell segment seamed with spun bell flare, depth 100. Valve type: standard three rotary valves and fourth valve; Valves are lever linkage, separate main and F tuning-slides.