Here is a tough pen that not only lets you write anywhere but also defend yourself. The Impromptu Tactical Pen has a window-shattering tip and machined steel design to get you out of trouble. The pen uses a “Rite in the Rain” ballpoint pen cartridge, which means you can write in all conditions.
This pen can be used to break a windshield or defend yourself when attacked. Costs $72 at this time.