Smoke detector :This small gadget will alert and warn people stay far away from danger field when it detected smokeWorking principle:It can detect the smoke by a couple of infrared diodes. The principle of detecting is that the granule in the smoke can reflect infrared light， and infrared diodes receive it， then the detector can give out alarm signal. The infrared diodes are placed in the ionization chamber for easy detection from all directionsEasy to install:Designed for the fastest possible installationApplication:It can be widely used in houses， offices or public places， like theaters， airports， restaurants， hotels and waiting rooms at railway stationsMaterial: ABSResponse Gas:Coal Gas， Natural Gas， Liquefied GasAlarm Concentration:Coal Gas: 0.1~0.5%; Natural Gas: 0.1~0.3%; Liquefied Gas:0.1~0.2%Work Current:100mAAlarm Indication:Red LED FlashPower Supply:1 x 9V battery (included)