http://www.uzi.com/tactical-pens/uzi-tactical-glassbreaker-pen-2-gun-metal
I took karate for a number of years and learned a lot. I always suggest to people, when in a potentially bad area, to walk with their car keys between their fingers. Two sets of keys? Both hands. Like brass knuckles. Go for the eyes....the throat....the temples.....the groin.
Thank you.