MQ4 GAS Sensor is suitable for sensing natural gas, Methane (CH4). MQ4 gas sensor is composed of micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer, measuring electrode and heater are fixed into a crust made by plastic and stainless steel net. The heater provides necessary work conditions for work of sensitive components. The enveloped MQ – 4 has 6 pin, 4 of them are used to fetch signals, and other 2 are used for providing heating current. This MQ4 Gas sensor is suitable for detecting Natural Gas concentration. It has a high sensitivity and fast response time. Sensor provides an analog resistive output based on Natural Gas concentration.