Glass breaker at top of pen. Constructed of aircraft aluminum. Uses standard Parker and Fisher space pen refills. Twist to open and close pen. 1 year manufacturers warranty by UZI. Not only to be used as a writing instrument but also as a glass breaker or also commonly known as a window punch. If your job ever requires you to get into or out of a vehicle quickly, you need one of the these tools. Designed to shatter auto glass on contact. UZI tactical pen with glass breaker.