CJRSLRB Gas Detection Module MQ-2 MQ-3 MQ-4 MQ-5 MQ-6 MQ-7 MQ-8 MQ-9 MQ-135 Sensor Module Each of Them 1pcs total 9pcs Sensor kit ICSG017A is a "Gas Sensor" module. The dual signal output (analog output and TTL output) The analog output and increased with the increase of concentration, the higher the concentration higher voltage; Has a very high sensitivity to sulfide, benzene vapor, smoke and other harmful gases Quick response and recovery characteristics