The Boker Plus Recoil Commando Pen designed by David Cyr and Kevin Passon has a spring punch secured under the front cap. In an emergency, it can be used to break glass in a safe and controlled way. Unlike other glass breakers, it doesn't have to hit the glass with force but is simply placed on the glass pane and pressed into it. The spring inside the pen is tensioned, which multiplies the exerted force. When the tip has recoiled deep enough into the pen, it shoots out again, breaking the glass.