The CJMCU-811 is an ultra-low-power digital gas sensor that integrates a CCS801 sensor and an 8-bit MCU with an analog-to-digital converter (ADC) to detect indoor air quality, including carbon monoxide (CO) and a wide range of Volatile Organic Compounds (VOCs).
More information:
https://www.banggood.com/CJMCU-811-CCS811-Carbon-Monoxide-CO-VOCs-Air-Quality-Digital-Gas-Sensor-p-1157216.html