18" - 32" adjustable. The pendant is approx 1" x 0.75".  The mantra "OM MANI PADME HUM" translates "the Jewel is in the lotus", meaning that enlightenment is in the everyday world. The purpose of mantras is to rebirth the self; a refreshment of the self. Mantras are a very powerful way to reduce negative energies and effects. Buddhist do believe that by chanting it may produce a force which will reduce negative karma, accumulate merit, rescue himself from suffering in next life.