9Pcs MQ2 MQ-3 MQ-4 MQ-5 MQ-6 MQ-7 MQ-8 MQ-9 MQ-135 Sensor Module each 1pc for arduino For ArduinoThe sensor need to solder onto board by yourselfDIY KitsMQ-2 Smoke Gas LPG Butane Hydrogen Gas Sensor Detector Module For ArduinoMQ-3 Alcohol Ethanol Sensor Breath Gas Detector Ethanol Detection for ArduinoMQ-4 Methane Gas Sensor Natural Coal Co methane detector module For ArduinoMQ-5 Methane Gas Sensor Shield methane detector module For Arduino UNO Mega2560MQ-6 LPG Gas Sensor Isobutane Propane Sensor For Arduino & RaspberryMQ-7 Carbon Monoxide CO Gas Sensor Module For Arduino UNO Mega 2560 A123MQ-8 Hydrogen Gas Sensor Module Gas Sensor module for ArduinoMQ-9 Combustible Gas Sensor Detection Carbon Monoxide Alarm ModuleMQ-135 Sensor Air Quality Sensor Hazardous Gas Detection Module ArduinoPackages:1 x MQ21 x MQ-31 x MQ-41 x MQ-51 x MQ-61 x MQ-71 x MQ-81 x MQ-91 x MQ-1351 x 20pcs 20cm male to female jumper cable1 x 20pcs 20cm female to female jumper cable