Smoke alarm; 1.9V Battery smoke alarm; 2.High sound 85dB(3m) smoke alarm; 3.Test button; 4.Low battery alarm; PW-507 Stand-alone photoelectric smoke alarm is under BSI approval, and can be calibrated into either UL, VDS, NF Standards. It features UL-approved Photoelectric sensing components with precise smoke detection. and long life (18 months) 9V battery operation (9V UltralifeLithium battery model for 10-year life is available too). 9V Power Supply, Meets CE, RoHS and EN14604 Specifications/Special Features: Features: Works on principle that infrared scatters on smoke surface Probes smoke which is generated by incomplete combustion at initial stage of fire Smoke detector consists of photoelectric system, signal processing identification and alarm circuit Infrared scatters on surface of smoke when smoke enters darkroom of detector Photoelectric diode receives scattered light and generates photoelectric signal current Photoelectric signal generates alarm signal after being processed by identification circuit, accordingly purpose of alarming is achieved Specifications: Power supply: 9V DC Block battery/PP3 Quiescent current: 8μA Alarm current:16mA Alarm decibel: �5dB/3m Sensitivity standard: EN14604 Age limit of battery: 2 to 5years(It varies with different types of battery) Temperature: -10 to +40 degrees Celsius Low battery Alarm High and stable sensitivity 5 years limited quality guarantee