KUBOTAN KEYCHAIN
The Kubotan is a short-range or close-quarter self-defence weapon used in joint manipulations, pressure point techniques, and strikes intended to hit the attacker's sensitive parts of the body. What looks to be a simple key fob is specifically designed to support the fist for punching, or used in short forward jabs or even in an ice pick style hammer fist strikes. Many martial artists practise the use of the kubotan keychain to increase the intensity of strikes, joint manipulations and pressure point techniques. The Kubotans are made from aluminium and comes with keychain ring to easily carry it around wherever you go. 
Can be used to keep keys
Super handy as a self-defence weapon
The ridges ensure a nice tight grip
Safer to carry around kids than pepper spray or stun gun