1Grove - Gas Sensor(MQ-2):Combustible Gas Smoke [medium sensitivity] 2Grove - Gas Sensor(MQ-3):Alcohol and Benzine [high sensitivity] Long warm-up 3Grove - Gas Sensor(MQ-5):LPG, Natural Gas, Town Gas [high sensitivity] 4Grove - Gas Sensor(MQ-9):LPG, CO, CH4 [low sensitivity] 5Grove - Air Quality Sensor(TP-401): CO, alcohol, acetone, thinner, others [high sensitivity]. 6 7Note - Gas sensors need to be heated, first minute the data is incorrect. Air 8Quality sensor needs 48h to stabilize. 9