This 8850 combustible gas detector is a useful tool in any environment where gasoline, natural gas, fuel oil, propane and many other explosive gases may be present. When a combustible gas or vapor source is approached, an audible signal increases in frequency and the red lights illuminate in sequence, to show the intensity of the leak. The flexible probe gives access to gas leaks in hard to reach places. This combustible gas detector is UL, CE, and MSHA approved.