Description : KERUI SD02 Wireless Photoelectric Smoke Fire Detector for Home GSM\/PSTN Auto Dial Alarm System Smog Sensor Features: Smoke detector is a device that detects smoke, typically as an indicator of fire. Commercial, industrial, and mass residential devices issue a signal to a fire alarm system, while household detectors, known as smoke alarms, generally issue a local audible and\/or visual alarm from the detector itself. Specifications: Battery: DC9V ( included) Alarm sound:>80Db ( within 3m) Working temperature:-10 C~55 C Working humidity: <95%RH Wireless frequency: 433MHz weight: about 135g Package includes: 1 x Smoke detector 1 x English user manual Details pictures : The smoke detector can use alone and can also be connected to the internet. On the emergency, it can not only alarm itself, but also can connect with the alarm host to alarm.