"The CRKT Williams Tactical Pen features aluminum construction with a non reflective black finish; a tapered body, a snap on cap and a shirt pocket clip. This CRKT Pen uses a Fisher Space Pen ball point cartridge (refill Fisher Space Pen #PR4); a pressurized design that allows for writing at any angle in freezing cold, boiling heat and underwater. The CRKT Williams Tactical Pen has a diameter of .63", an overall length of 6.00" and it weighs 1.2 ounces. This tactical pen is a high-tech writing instrument that can be used as self-defense enforcers if need be. With some basic instruction or knowledge, one can readily use the pens against an assailant or attacker to inflict notice, pain or injury - thwarting an otherwise potentially defenseless act."