The frets
From the second half of the 19th century, the rudra-vina has between 21 and 24 frets and their pitch, just as their shapes and the thickness of the metal slides, is variable from one instrument to the other. On some instruments, they are attached to the tube with fine cords of waxed flaxen threads.
To ensure that they are firmly fixed, the frets are provided with a notch in the middle of the convex curve. The notch fitted into a central track that extended all along the tube.
Other processes more or less provisional though they were materialised towards the end of the 19th century; such as mobile frets, each equipped with a nut for tightening that would lock on the central track. This experimental system allowed the positioning of each fret in the exact desired location.