Some Inflatable PFDs use this Green Arming Pin as an indicator that the CO2 inflation cylinder is unused and ready to inflate the PFD when needed. When the cylinder is punctured, the Green Pin breaks and falls away. The Green Pin is fairly fragile. Store it carefully so that it doesn't get damaged. The pin must be fagile so that it doesn't interfere with activation of the inflation mechanism. Kit Includes 4 Arming Pins.