KIDDE 21006377-N Smoke and Carbon Monoxide Alarm. More details: Smoke and Carbon Monoxide Alarm, Detection Method Ionization, Electrochemical, Up to 24 Units Interconnection Capability, Power Source 120VAC, 9V, Audible Alert 85dB @ 10 ft., Horn, Visual Alert Red LED, Diameter 5-3/4 In., Height 1-3/4 In., Digital Readout No, Battery Backup Yes, Features Voice Warning, Peak Level Memory, Reset Button, Hush Button Yes, Locking Pin Yes, Operating Temp. 40 Degrees to 100 Degrees F, Standards UL, Includes Mounting Anchors and Screws