With a unique optical sensing chamber designed to sense smoke particles produced by a wide range of combustion source Features1) Advanced photoelectric smoke sensing technology2) Sleek ergonomic design3) Very loud alarm horn 4) Test button for verify battery status and alarm operation5) Low-battery warning6) Mounting bracket and screws7) Easy install, move and maintain.8) Meet UL217 standardOptions1) OT701: basic  2) OT701A: AC110/220/230V3) OT701B: Battery backup4) OT701R: Relay output5) OT701I:  Interconnection function allows for up to 20 additional units. If one of the detectors senses smoke, all of the interconnected detectors will also alarm hazardous situation. SpecificationsPower Supply: 9V Battery or AC100/110/120/220/230/240V,50/60Hz     Sensitivity: 2.72±0.99%/FTBattery Life: At least 18 months (GP alkaline battery) or 12 months (Carbon Zinc) under normal conditionsLow Battery Life: Up to 30 days warning signal        Alarm Sound Level: Exceeding 90dB at 10 feet                               Dimensions: Diameter 138 mm  Height 48.5 mm     Weight: ~235g (include base and battery)Operating Environment: Temperature: 0°C~50°C   Related Humidity: ≤95%   

Stand-alone Smoke Alarm (9v battery)