The Tactical Writing Instrument TWI-01 from Hardcore Hardware Australia is made from aluminum with knurling along the pen body to ensure comfortable grip. It is outfitted with a stainless steel dome-shaped crown for use as a glass break in an emergency situation and the pointed tip at the other end can be used as a PDA stylus. The TWI01 includes a series of O-rings making it completely waterproof when the cap is screwed down over the writing tip. The TWI01 will accept standard Parker and Fisher Space Pen refills.