If you’re reading this at home, chances are you can look up from the screen and see at least one smoke detector. These life-saving devices are able to alert you to smoke from a fire, letting you get out before it’s too late. Weather radios do the same thing for hazards like tornadoes and floods. Every home, school, and business in the United States needs to be equipped with these critical devices that let you act before hazardous weather strikes.

Anyone who’s listened to television or radio over the past five decades is intimately familiar with that horrible, chill-inducing noise of the Emergency Alert System. Aside from catching your attention, that nails-on-a-chalkboard screeching serves a useful purpose that calls back to the days of dial-up internet.