These keychains are awesome. It tells you if you are close to radiation or not. This $100 keychain's integrated sensor samples the air 32,768 times per second to let you know how much radiation you're taking in. If you hear two long beeps, the radiation level is relatively low. A long beep followed by a short beep means you should dig yourself a shelter immediately. And if you hear two short beeps in a row, you may already be dead.