Bhairav Raksha Kavach is associated with the Kal Bhairava form of Mahadev Shiva. The common belief is that those people wearing the amulet will be protected and blessed by Bhairava. It protects people from the fear of ghosts and darkness.
Bhairav Raksha Kavach is also widely used by people who believe that their progress is hampered by mantras and tantras of their enemies. The belief is that the person who wears the kavach is invisible to enemy mantras and tantras.
It is also worn for good health, to wipe out thoughts of failure and to overcome lethargy.