The Shruti Box is a drone instrument. The bellows on the side pump air through a set of reeds creating a constant tone. The notes are changed using the manually operated stoppers.
This Shruti Box has a total of 12 reeds with 3 different combinations of the notes i.e. Sa (1st note), Ma (4th note), Pa (5th note), Sa (8th note - next octave). The Male pitches are in the lower octave whereas the Female pitches are in the higher octave.