General Tools PNG1 Combustible Gas Detector is ideal for detecting natural gas (methane), propane or butane from tanks, plumbing and appliances. This handy pen type gas detector is a necessity for every household. Features different alarms for leaks, sensor fault and low battery. It is sensitive, reliable and easy to operate. Fast response and fast resume. Automatically sets zero measurement baseline upon startup in fresh air. Redundant visual and audible alarms. Double molded hand grip. Range is 0 to 100 percent LEL (Lower Explosive Limit). Low alarm (20+/-5)% LEL to (50+/-5)% LEL. High alarm > (50+/-10)% LEL. High/Low Audible Alarm Levels > 65dB. Sampling technique is natural diffusion. Operating temperature is -4 to 131 degrees Fahrenheit (-20 to 55 degrees Celsius) at 95% RH. Includes wrist strap, User's Manual, batteries and 1-Year Warranty. Power source is 2 AA batteries (included).