Pellet drums, or rattle drums, are a class of membranophone, or drum, characterized by their construction and manner of playing. They have two heads (either a single double-headed drum or two hemispherical single-headed drums joined together with the heads facing outward), and two pellets, each connected by a cord to the drum. The damaru, which is used in Tibet, Mongolia, and India, is an hourglass drum that is grasped by its waist with the hand twisting back and forth, causing the pellets to strike the heads in a rhythmic fashion.^{photo]/sup> In China, Korea, and Japan, pellet drums are affixed to or pierced by a vertical rod or pole, and, depending on the instrument's size, the rod or pole is rotated back and forth along its axis either with one or both hands or between the palms, causing the pellets to strike the heads in a similar manner.}