Stun Gun description

"A non-lethal weapon that delivers a 1.5 million volt electric shock to the target, overloading their motor neurons and rendering them unable to move. Shocking the target long enough will knock them unconscious.
By making use of conducting materials (water, metal), it can be used to shock more distant targets as well.
Charging the rod takes a short while, so it cannot be used multiple times in a row. Keep this in mind when facing multiple enemies.
Useful when going for a no-kill completion, or when ammo is running short for your other weapons."
―Stun Rod weapon description in Metal Gear Solid: Peace Walker