Prayer wheel is also called Mani Wheel. Buddhist used prayer wheel or Mani Wheel to spread. spiritual blessings. Prayer wheel is a cylindrical object embossed with mantra in a thin paper rolls. Om Mani Padme Hung mantras are printed on paper and some time outside the cylinder. Prayer wheel brings great blessings, crates enormous and powerful karma.
Prayer wheels were first invented because many in Tibet could not read, and this was a way to get their prayers out even though they could not read them out. It is said that for every rotation of the wheel you can chant Om Mani Padme Hung.
One of the benefits of the prayer wheel is that it embodies all the actions of the Buddhas and Bodhisattvas of the 10 directions. To benefit sentient beings, the Buddhas and Bodhisattvas manifest in the prayer wheel to purify all our negative karmas and obscurations, and to cause us to actualize the realizations of the path to enlightenment. All the beings (not only the people but also the insects), in the area where the prayer wheel is built are saved from rebirth in the lower realms; they receive a deva or human body, or are born in a pure land of Buddha.
There are different type and size and design of Tibetan Prayer wheel or Mani wheel available in market. Not all prayer wheels are hand held.