The small brass or steel hammer used for tuning. Taps on the gajra from above raise pitch; from below, lower it; heavier blows reseat the gatta blocks for coarse changes. The dayan is tuned to the tonic of the performance — checked around the full circle of the head so every Na speaks the same note.
Hammer technique is itself taught: glancing, controlled taps, never blunt force near the skin. A player's hathodi lives in the instrument bag next to spare straps and powder.