Prayer wheel...

"A prayer wheel is a cylindrical 'wheel' (Tibetan: 'khor) on a spindle made from metal, wood, stone, leather, or even coarse cotton. Traditionally, the mantra Om Mani Padme Hum is written in Sanskrit externally on the wheel. Also sometimes depicted are Dakinis, Protectors and very often the 8 auspicious symbols Ashtamangala. According to the Tibetan Buddhist tradition, spinning such a wheel will have much the same meritorious effect as orally reciting the prayers. It is said that prayer wheels are used to accumulate wisdom and merit or good karma and to purify negativities such as bad karma. The practitioner most often spins the wheel clockwise, for the direction the mantras are written is that of the movement of the sun across the sky."

Text in: http://en.wikipedia.org/wiki/Prayer_wheel