Silver Cobra Koga Keychain Self Defense. The practically indestructible aluminum design can be used and reused many times. Unlike a stun gun or pepper spray, this self defense key chain does not require a battery, canister, or periodic testing. It is plain hard metal and consistently will remain the same. The pointed tip multiplies impact force from a strike. These are also used to perform submission holds, joint locks, and improve leverage. Concentrate your defensive strength with this Cobra Koga key chain, and easily keep it with you. Overall Length: 6 Inches. Diameter: 14mm. Features: Blunt Pierce Spike, Four Finger Handle Grip, Key Chain. Construction: Aluminum.