Nighthawk Plug-in Carbon Monoxide & Explosive Gas Alarm with Digital Display  KN-COEG-3 Protects you and your family from two deadly threats: carbon monoxide and explosive gas. Sounder Alarm  The KN-COEG-3 offers a loud 85-decibel pulsing alarm that will sound to alert you to a potential problem. Digital Display - Displays the level of carbon monoxide the unit is sensing. Peak Level Memory - Recalls the highest CO concentration detected Test/Reset Button - Tests units electronic circuitry operation and allows you to immediately silence the alarm Two alarms in one detects carbon monoxide and explosive gas Three convenient mounting options Digital display and peak level button displays the peak CO level recorded by the alarm since it was last reset Battery backup 9 volt battery included Kiddes carbon monoxide alarms meet the requirements of Underwriters Laboratories (UL), an independent facility that tests products for compliance with widely-accepted safety standards