Wall-hung household gas alarm designed to detect the concentration of combustible and toxic gases or vapors.it provides a visible and audio signals when the gas concentration reaches presetting level,reminds you take prompt favorable ing voltage:ac220/110v+/-10 or dc12/24v<=2wworking Conditions:tem-10c-50c,hum:<95%rhdimensions&weight:125x70x35mmsensor type:semiconductor or catalytic sensorresponse time:20sec for combustible gas,2.5min for co