This is one of those little things that many agencies suggest a home emergency kit should contain. Including a compass, a waterproof storage compartment for matches and a signal mirror, it seems more suited to lost campers. However, if, God forbid, you should find yourself trapped under debris after an earthquake, a whistle, which hangs on a lanyard around your neck, will help rescuers locate you more quickly. It costs $2.44 on Amazon.