It has a cylindrical bore and four Perinet valves. Its length is 86 cm and the bell diameter is 17 cm. The "valve" nearest the mouthpiece on the leadpipe controls a silk membrane to create a nasal effect, which Sudre designed to make a sound like a cello or a violin. The instrument is very similar to the baritone horn and helicon. Acoustically these resembled the saxhorns, but the shape was different as the main tube was doubled back on itself, giving a vertical appearance.