Carbon Monoxide Alarm, Battery Chemistry Not Applicable, Battery Location Not Applicable, Battery Locking Pin No, Battery Size Not Applicable, Communication Protocol Not Applicable, Compatible With 4 Wire Fire Alarm System, Detector Type CO Detector, Features Six Year End-Of-Life Timer, Low Current Draw of 20mA in Standby and 40mA in Alarm, Full UL 2075 Compliance, Includes (4) Mounting Screws, Number of Tandem Detectors 2, Power Source Hardwired, Sensor Type Electrochemical