Together with the bell, the Dorje or Thunderbolt is the attribute of the Vajrasattva Buddha. The Dorje symbolizes the eternal, the absolute, that which cannot be destroyed.
In the Vajrayana context, practitioners utilize the bell and dorje as important symbolic ritual items. We hold the dorje, or vajra, always in the right hand, while we ring the bell with the left hand. At the outer level, these two implements represent the indivisibility of means (vajra) and the wisdom recognizing emptiness (bell). At the same time, we can understand that the dorje represents compassion, while the bell signifies Prajñāpāramitā, the perfection of wisdom.