Technical description: Ebonite with nickel plated german silver ferrules and keywork. Five pieces: mouthpiece, barrel, upper section, lower section, bell. Stamped ebonite mouthpiece presumably original and marked for a ligature. Curved speaker with a chimney on the front of the instrument. All tone-holes under rings raised and lined with german silver. Brille on upper section with vent at R1. Articulated C♯₄/G♯₅, activated by L4 (attached to the bascule key, correspondence also to F♯₃/C♯₅), closed by R1. Alternative F₃/C₅ for L4 also operating C♯₄/G♯₅. All these features should avoid gliding for L4. C sharp mechanism. 14 keys, 5 rings, 4 black rollers.
L0: T; speaker.
L1: T + ring; throat A♮; throat A♭.
L2: T + ring.
L3: T; cross E♭₄/B♭₅.
L4: E₃/B♮₄; F♯₃/C♯₅; F₃/C₅.
R1: T + ring; side F₄/C₆; side E♭₄/B♭₅; side trill key 1-2.
R2: T + spectacle.
R3: T + spectacle (forked B♭₃/F♮₅); cross B♭₃/F♮₅.
R4: G♯₃/E♭₅; F₃/C₅.
Keyhead type: modern.
Keymount type: screwed in pillars.
Very similar to B♭ clarinet (5344) and A clarinet (4770).