... :https://www.amazon.com/Portable-detector-measure-display-combustible/dp/B01IET7OC0?ie=UTF8&*Version*=1&*entries*=0Xi'an Hua Fan Instrument Co.,Ltd ... in China, welcome to buy or wholesale gas alarming detectors, CO detector, carbon monoxide detectors made in China from us.Product ... )Destination gas: oxygen (O2), gas (EX), poisonous and harmful gases (CO, H2S, NH3, CL2, etc.)Response time: ≤30s(O2);≤40s ...