Smoke Alarm Detection Method Photoelectric Up to 24 Units Interconnection Capability Power Source 120V AC 3V Lithium Audible Alert 85 dB @ 10 ft Visual Alert Style LED Diameter 5 19/32 in Height 1 29/32 in Depth 1 29/32 in Width 5 19/32 in Digital Readout No Battery Backup Yes Features End of Unit Life Warning Hush Button Yes Locking Pin No Operating Temp 40 Degrees to 100 Degrees F Standards UL 217 Listed CA State Fire Marshal Listed Manufacturers Warranty Length 10 yr