Not everyone keeps an emergency tool in their vehicle. This simple bracelet ensures you can escape via a side or rear window. On its elastic cord sits a striker bead made from tungsten carbide, the same material used in armor-piercing ammunition. To use it, simply pull it from your wrist, wrap the loop around your thumb and first finger, place the bead against the window, then pull back and release it. Just a single strike should be enough to destroy the glass and give you a path to safety.