The Extech EZ40 EzFlex Combustible Gas Detector features a 16-inch gooseneck for easy access to hard-to-reach areas. The detector has a high sensitivity and can be used with one hand, using thumb-controlled sensitivity changes to eliminate background gas levels. It has a visible and audible alarm at 10% (LEL), the lower explosive limit for methane. This gas detector will help you find even the smallest leaks. Complete with three C batteries.