The Vajra is a legendary and ritualistic tool, symbolizing the properties of a diamond and a thunderbolt. It is also described as a "ritual weapon".
The use of the bell and vajra as symbolic and ritual tools is found in all schools of Tibetan Buddhism. The vajra is a round, symmetrical metal scepter with two ribbed spherical heads. The ribs may meet in a ball-shaped top, or they may be separate and end in sharp points. From Wikipedia
