The Kidde 900-0076 (model KN-COPP-3) is a 120 VAC powered, plug-in carbon monoxide alarm with battery backup and a digital display. The KN-COPP-3 is an easy to install unit that provides reliable protection against the dangers of carbon monoxide. The 900-0076 will detect and store measured data of concentrated CO levels as low as 11 and up to 999 PPM with its peak level memory display. This alarm gives you several mounting options, including direct-plug, a 6 ft power cord or table top. Displays the level of carbon monoxide the unit is sensing The unit updates this reading every 15 sec Test/reset button tests unit's electronic circuitry and horn and resets the unit during alarm Peak level button displays the peak CO level recorded by the alarm since it was last reset or unplugged 9 V battery back-up provides protection during a power outage