Carbon Monoxide and Smoke Alarm Battery Chemistry Alkaline Battery Location Back Battery Locking Pin Yes Battery Size 3V Communication Protocol Not Applicable Compatible With Not Applicable Detector Type Smoke/CO Detector Features Photo Electric Sensor and 10 yr Tamper Proof Lithium Power Source Includes Mount Bracket Number of Tandem Detectors Not Applicable Power Source Sealed Battery Sensor Type Electrochemical Ionization Visual Alert Type Red LED Volume Level 85 dB @ 10 ft