Carbon Monoxide Alarm Battery Chemistry Alkaline Battery Location Back Battery Locking Pin No Battery Size 9V Communication Protocol Not Applicable Compatible With Not Applicable Detector Type CO Detector Features AC Plug-In Power and Battery Backup Includes 9V Battery Number of Tandem Detectors Not Applicable Power Source Removable Battery Sensor Type Electrochemical Visual Alert Type Digital Display Volume Level 85 dB @ 10 ft Accuracy +/-20 Percent +15 ppm (CO)