First Alert PR710 Sealed Battery Smoke Alarm, White, 3 VHighlights: Type: Sealed Battery Voltage Rating: 3 V Battery Type: Lithium Sensor Type: Photoelectric Sound Level: 85 DB Operating Temperature: 40 100 Deg F Display: LED Standards: UL 217 Photoelectric sensor helps reduce nuisance alarms and detect slow smoldering fires Tamperproof, sealed alarm design, constant protection since battery cannot be removed Meets code for sealed tamperproof alarms, ideal for rental properties Patented smoke entry system