Tremolo Tuned Harmonicas
Tremolo tuned harmonicas produce a sound by simultaneous vibration of two reeds in a double hole, tuned with a slight difference in the tonality, resulting in a pleasant tremolo sound.
Tremolo and Octave tuned harmonicas do not easily allow the techniques of bending, overblowing, and overdrawing, and are therefor not recommended to be used to play blues or rock styles. They are generally used to play certain types of folk and ethnic music.
The models are quite different in their form, sonority, and tuning.