Because Halo and Halo+ (formerly Halo WX) alert users to multiple kinds of dangers, our devices emit different lights based on the type of threat they detect. Here’s the breakdown of which colors means what: Red When Halo detects concerning levels of smoke in your home, it will begin slowing pulsing in a red hue. As the smoke level increases, the speed of the light’s pulse will accelerate. Red + White If the threat has not been resolved and the smoke detected has reached a dangerous level, the red pulse will change to a red and white flashing light which is also accompanied by auditory warnings. Amber When carbon monoxide (CO) has been detected, your Halo will begin slowly pulsing an amber light and, as with the smoke detection, the speed of the pulse will accelerate as the level of CO increases. Amber + White If it becomes unsafe for you to be in the room where CO has been detected, the orange pulse will turn to an orange and white flashing light, along with an auditory alert: "Danger, CO in the living room, move to fresh air." Blue When Halo+ receives a tornado watch, the device will emit a blue pulse. Blue + White If a tornado watch in your area turns to a tornado warning, then the blue pulse will change to a blue and white flashing light. Halo not only uses these colored lights to indicate threats, but also emits specific verbal warnings to inform families when a threat has been detected. In addition to the standard light settings, our Halo devices can be programmed to emit lights in many different colors based on your weather & safety needs, such as for other programmed warnings on Halo+, as well as practical needs such as nightlights for your children.