It is widely used for household, especially no smoking places with intellectual alarm host to prevent fire, it can send the radio signal to alarm host when detects smoke hedonism. It will alarm and dial the pre-set alarm telephones with red LED in these situations: 1. The smoke density and time reach the limit. 2. Press the "test" button Features and specifications: 1) Special SCM intelligent controls, self-detecting, strong reliability, and easy installation 2) Relay normally opened/closed signal output and resumes automatically 3) Can be linked to home security system 4) Power: 9~15V DC, 24V optional 5) Static current: <0.02A 6) Alarm current: 95dB 9) Monitoring area: 20sqm 10) Self-detecting LED: 1.67s 11) Working temperature: -10 ~ 45oC 12) Relative humidity: < 95% 13) Material: ABS