Blue MQ-7 MQ7 CO Carbon Monoxide Gas Sensor Module For Arduino Compatible Detection Zone:10 to 1000ppmm Characteristic Gas:100ppmm co Sensitive Resistance:2K to 20K in 100ppm co Heating Voltage:5.0V0.2V /1.50.1V Size: 3.5cm X 2.2cm - 1.4inch x 0.9inch