1. MH-Z19B carbon dioxide gas sensor uses the principle of non-dispersive infrared (NDIR) to detect CO2 in the air. It has good selectivity, no oxygen dependence and long service life. 2. Built-in temperature compensation, digital output and waveform output at the same time, easy to use. 3. High sensitivity, high resolution, low power consumption, excellent stability. 4. Provide multiple output methods such as UART and PM waveform. 5. Widely used for HVACR and indoor air quality monitoring. Product name: CO2 Sensor Detection gas: carbon dioxide Working voltage: DC 3.6-5.5 V Average current: less than 18mA Interface level: 3.3 V Measuring range: 0-0.5% Output signal: UART, PIM Warm-up time: 3 min Response time: Tless than 60s Working temperature: 0-50 Celsius Working humidity: 0-95% RH (no condensation) colour:Golden Material:plastic size:27 x 22mm Package Contents: 2 x MH-Z19B Infrared CO2 Sensor Module Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is 1-3cm. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-Dadangjia