The MQ-7 is a Carbon Monoxide (CO) sensor.Technical parameters:Size: 32X22X27mmMain Chip: LM393, ZYMQ-7 gas sensorOperating Voltage: 5VDCInput Voltage: 5VDCPower: 150mA (note that the heater must be on for at least 30 seconds before readings are valid)DO Output: 0 or 5V. Trigger level is set using the onboard potentiometerAO Output: 0-5V depending on the quantity of CO present. See datasheet for detailsMQ-7 Datasheet