Kidde KN-COPP-B Front Load Battery-Operated Carbon Monoxide Alarm with Digital Display Digital display displays the level of carbon monoxide the unit is sensing Large backlit display is easy to read even in low light conditions Peak level memory displays the highest CO concentration measured since the last reset Front load battery door allows you to change battery without removing alarm from the wall Kidde's carbon monoxide alarms meet the requirements of Underwriters Laboratories (UL), an independent facility that tests products for compliance with widely-accepted safety standards