Cobra Tec's OTF Tactical pen is one of a kind. It is made of T6061 aircraft grade aluminum. It has a switch that you push up to deploy the 1.75 inch 440C stainless steel blade and push down to retract. It comes with a safety feature to prevent accidental discharge. It is also a writing pen and comes with a extra ink cartridge. This OTF Tactical pen is a great self-defense tool.