Boomwhackers Boomwhackers Tubes Treble Extension Set,Set Of 7Boomwhackers are one of the most popular musical learning tools in classrooms and music therapy sessions around the world! Color coded plastic tubes are cut to the exact length in order to create the eight pitches in a diatonic scale: c to c, or, do, re, mi, fa, sol, la, ti, do. The sound is created by striking the tube against any surface: a chair, the floor, your other hand theres lots of room to get creative!