... concentration using a simple circuit.MQ-2 gas sensor for liquefied petroleum gas, propane, high sensitivity of hydrogen, ... variety of applications.Module applications:Gas leak monitoring means, suitable for liquefied petroleum gas, butane, propane, methane, smoke, etc., ... natural gas, city gas, smoke better sensitivity.6, there are four screw holes for easy positioning;Product Dimensions: 36 (L) * 19 ...