They are worn around the neck and are attractive enough to be worn as jewelry and small enough to be worn discreetly beneath clothing if you prefer. The amount of mantras contained in a single prayer wheel is shown below. According to the Mani Kabum, which contains a short explanation of the lineage of the prayer wheel practice, Nagarjuna gave the practice to the Lion-faced Dakini, who gave it to Padmasambhava, who then brought it to Tibet. One of the benefits of the prayer wheel is that it embodies all the actions of the Buddhas and Bodhisattvas of the ten directions. To benefit sentient beings, the Buddhas and Bodhisattvas manifest in the prayer to purify our negative karmas and obscurations, and to cause us to actualize the realization of the path to enlightenment.
Prayer wheels use movement to generate merit and spread auspiciousness.
Just spinning a pendant prayer wheel for three to five minutes will release over one hundred million mantras or prayers. The power of a spinning prayer wheel can alleviate and remove suffering and create enormous merit. Whenever you spin your prayer wheel, you are generating from hundreds of thousands to millions of mantras and prayers, extending the blessings and merit they create, to yourself and all beings in all six realms. As with any practice it is essential to always dedicate the merit. Think of the benefit of spinning your prayer wheel just several times in a crowded subway car or bus.