Pocket Shark Sharpie by Cold Steel
At first glance, the Pocket Shark by Cold Steel shares many features common to most markers, but appearances can be deceptive. For starters, it's made from high impact plastic and features walls that are 4 times thicker than similar markers. This means it's built for impact and, in a self-defense emergency it can become an efficient Yawara stick for driving off an attacker. Plus, the screw-top cap will stay in place and won't pop off like a regular marker's cap would when you strike a percussion blow, or when obtaining joint locks or submission holds. The Pocket Shark is easy to carry too. Just clip it to a shirt or coat pocket, or carry in your purse, pack or brief case. Don't spend another day without one!
It actually writes, too. No refills however.