This battery operated Carbon Monoxide Alarm can prevent you from the effects of a gas that is one of the most deadly gases known. Carbon Monoxide is poisonous, odourless, invisible and you can neither smell or feel the gas. It is most common around inefficient burning devices such as boilers, and fires (whether it is gas, wood, coal or oil burning). Specification: 1) Power Source: DC9V battery 2) Standby current: <= 35uA 3) Alarm density: 150+/-50ppm CO gas 4) Alarm current: < 30uA 5) Sensor: use newest importing electrochemistry carbon, monoxide sensor, it more accurate, more credibility, good at refrain 6) Superbright LED display: flash every 30 seconds, When it at standby status, flash quickly when CO leakage 7) Lound buzzer output: 85db at 3M distance 8) Low voltage test: 7.5V 9) Work environment: -1o C~50o C; 20~95%R. H.