The stuffed ring cushion a drum sits on — also called gudri or gaddi. It keeps the round-bottomed shells stable, sets playing height and tilt, and isolates the shell from the floor.
Tilt is a real playing variable: the dayan is typically angled slightly away from the player, the bayan kept flatter for wrist and heel work. Well-made cushions hold their shape under hours of playing; collapsing ones quietly ruin posture and stroke angles.