3306/3308 Combustible Gas Leak Detector detects the presence of combustible gas and measures concentrations between 0~10000 parts per million (PPM). The Detector indicates the presence of combustible gas by a reading on the LCD (3308) or five red LEDs (3306), The five red LEDs indicate different concentration of gas. The beeper function much like clicking of a Geiger counter: Above 3200 PPM, the beeper sounds continuously with the concentration of gas. From 0 PPM to 3200 PPM, the beeper will sound rapidly due to the increasing concentrations of combustible gas. It provides quick, precise gas leak locating, would be the best instrument for explosion preventing and safe production.