General Tools PNG2000A Natural Gas Detector Pen Handheld natural gas detector is sensitive, reliable and easy to operate; detects LNG, LPG, CH4, methane, and butane gas Gas detector has an LED light that indicates how severe the gas leak may be; green signals on, yellow indicates 200-Ppm, red indicates 500-Ppm Gas sniffer comes has catalytic combustion sensor; multiple home and commercial uses for detecting the unseen presence of dangerous natural gases Gas leak detector comes pre-calibrated; the detection tool is ready for us right on arrival Unlike other natural gas leak detectors ours is compact and lightweight and can be taken on the go