Tactical Black Screw Cap, Glass Breaker Tip Pen with Flashlight. Flashlight runs on 3 LR754 button cell batteries, included. This is a real writing pen with a pointed glass breaker tip which can be used in self-defense situation to jab or stab. The opposite end has a bright 100 lumen flashlight. The flashlight end also has a edge that when jabbed or scraped on an attacker can be used as a DNA collector. Pen Measures 6 1/4" x 1/2"