This is a simple-to-use compressed natural gas (CNG) sensor, suitable for sensing natural gas (composed of mostly Methane [CH4]) concentrations in the air. The MQ-4 can detect natural gas concentrations anywhere from 200 to 10000ppm. Specification: Signal output indicator Dual Signals output (analog output and TTL output) TTL output signal is low level, allows to Read more about MQ-4 High Sensitivity Gas Methane Detector Sensor[…]