Sensitive material of MQ-2 gas sensor is SnO2, which with lower conductivity in clean air. When the target combustible gas exist, The sensor's conductivity is more higher along with the gas concentration rising. Please use simple electrocircuit, Convert change of conductivity to correspond output signal of gas concentration. MQ-2 gas sensor has high sensitity to LPG, Propane and Hydrogen, also could be used to Methane and other combustible steam, it is with low cost and suitable for different application. Wide detecting scope Stable and long life Fast response and High sensitivity Simple drive circuit The Grove - Gas Sensor(MQ2) module is useful for gas leakage detecting(in home and industry). It can detect LPG, i-butane, methane, alcohol, Hydrogen, somke and so on. Based on its fast response time. measurements can be taken as soon as possible. Also the sensitivity can be adjusted by the potentiometer. Specifications - Detection range: 300 to 10000 PPMM Characteristics of gas: 1000 PPMM isobutane Sensitivity: R in air/Rin typical gas >=5 Sensitive resistance: 1k ohm to 20k ohm in 50PPM toluene Ambient temperature: -20? ~ + 55? Measure the voltage<=24V