New Multi-functional Pen Tactical Self Defense Pen Survival Portable Outdoor Camping Tool 6061-t6 Aviation Aluminum The military aviation aluminum material is not only a writing tool but a good self - defense, glass breaker tool. Can also be used in an emergency to break The window, help to escape. Material: 6061-T6 Aviation Aluminum Length:14.8 cm; Diameter: 1. cm. Durable and practical,and just rotate the pen holder to write