The 3-in-1 seat belt cutter is a small versatile tool that can save your life in case of emergency,it is lightweight with key chain and easy to carrying. SOS whistle:asking for help with high decibels sounds in emergency. To cut the seat belt:the safty blade can be used to cut the seat belt in case of emergency. To break the window glass: in case of emergency,you can use the tool to break the window glass,remove the cap of the tool,press the trigger of firing pin against the window until it clicks