Electrochemical sensor technology detects CO gas Easy installation, no wiring needed: operates on a 10-year lithium battery, so it never needs replacing, plus detects during power failure Conveniently designed & portable: simple to install on a wall of your home or place on a tabletop 85-decibel alarm alerts to carbon monoxide 3 LEDs indicate: green = normal operation, red = carbon monoxide presence, & amber = replace the detector Test-Hush button makes it easy to test the carbon monoxide detector or temporarily silence the low battery chirp warning UL Certified, 10-year limited manufacturer warranty