by the way ... in terms of deterrence on the street and effective against some animals - a good stun gun is also a possibility. check the Barracuda BC-37 stun gun ... these babies are head-and-shoulders above the competition. If you are being threatened by punks who look like they want to use their fists - just take it out and give them a display of the electrical flash. It's enough to make anyone think twice about tangling with you. If you do actually use it on people, I would recommend contact with the extremities, or possibly the back or hips (not head, neck or chest). These things pack a wallop.

cheers,
Pete2