Associated with Tibetan Buddhism (see Tibet), this is a metal cylinder packed with printed sheets of mantras that pivots on a spindle or handle. When rotated, it is believed that the power of the mantras is ‘activated’ and they bestow protection and merit (puṇya). Prayer wheels are usually small hand-held objects, although larger wall-mounted ones are seen. Some prayer wheels in Tibet were water-powered.
Fig 16 prayer wheel