The six examples are all probably pitched in C (D-Leipzig, 1538; B-Bruxelles, 940; US-MA-Boston, 17.1879 (unstamped); US-NY-New York, 89.4.2345 (unstamped); F-Paris, E.760, C.550; I-Roma, 617). The first four examples have five brass keys: S, A, Ab/Eb,F#/C#, and E/B as found on soprano clarinets with the S and E/B keys positioned on the back for the left and right thumbs. There are six sections: mouthpiece, curved section similar in shape to the Greek letter omega (Ω), barrel, body section with finger holes and one thumb hole bored at an oblique angle, bell base, and bell flare. The length and bore of the long serpentine body produce a sound an octave lower than the soprano clarinet.

Three of the six Papalini bass clarinets (B-Bruxelles; US-MA-Boston, ca. 1825; US- NY-New York, ca. 1825) show a later design. They have a boxwood barrel with horn ferrules connecting the omega sections to the main body. The two halves of the body and omega sections of the Brussels example are connected with wooden pins, the Boston example has iron pins, and there are no pins in the New York example.

On the Brussels instrument, there is an oval resonance hole not covered with a finger, toward the outside of a curve below L3, and another on the bell to correct intonation. Each of the finger and keyholes is numbered one through nineteen; “NICOLA/PAPALINI/INVENTORE” is stamped on the lowest bulge of the instrument, next to the bell

Rice, From the clarinet d’amour to the contra bass, 284,285.