Bb bass clarinet
Transposing instrument (Bb).
Transposition up a diatonic 9th from concert (an octave and a diatonic 2nd).
Scored in bass clef. The parts are extracted to treble clef.

The bass clarinet high range is playable, though usually to the detriment of the woodwind section. Every section needs its bass instruments playing bass. Make sure you are an experienced arranger before you choose to write the bass clarinet high.