for the first time : Plug the detector into 90V-240V power, the colour Power Led fall up and the amount Alarm Led will flash for 3 minutes, please wait and when the amount led indicator is forth, the detector go to the formula working state.Alarm : When the gas concentration is over 2500PPM, the buzzer will make a continue measure as `` Di Di Di '' and the amount indication fall will flash.Technical Parameter : 1. AV : AV 90V-240V 50-60Hz2. Battery : 9V reversible battery -LRB- nonmandatory -RRB- 3. excavation : 0-50 ?. . Environment : 10 % -95 % 5. Alarm Density : -LRB- ± 1500PPM -RRB- 6. Alarm : keep terrific after over 2500PPM7. : Approx112x73x42MMNotice : 1. The gas detector is to be effected by the sewing needle pounding and shock in transit or installation, hash out to not work .2. This a combustible material Gas Detector, can not detect the malevolent gas so much as CO. 3. Scheduled maintenance : surface per month, specialist inspection per half year. . . Do not use the detergent to plum the gas detector, this will the gas detector. . . not spray any sprays so much as air freshener, hair spray, etc. 6. This product is only to reduce the accident, can not make certain everytime. Except use our in alter way, please also pay more attention in your every day life and strengthen safety and security conciousness. Package : 1x Gas Detector Alarm Sensor1x Product ManualWe have passed the CE & ROHS Certification and EN50194 .