This is a hand held battery powered device that has one purpose only, to stop an attacker in his/her tracks.
Stunguns are designed to deliver an intense electrical shock into an attackers body via two prongs that are part of this very effective self defense mechanism.
Pressing the prongs on the stun gun against a person will quickly immobilize an attacker by causing an intense pain and complete loss of muscle control. No serious or permanent injury is lasting on the attacker, they will simply be immobilized for a few minutes.