SCD4x CO2 Gadget

The Sensair gadget is more accurate than most CO₂ Mets in this price range, especially if allowed to reach levels close to outdoor CO₂ levels periodically. It can be a little loose in the USB port but a short piece of gaffer tape is all you need to hold it securely in place. The smartphone app allows for downloading longer term data (fyi data is erased when it gets unplugged, so download regularly or before disconnecting). The readings have been consistent with Aranet4, InkBird, Qingping, and AutoPilot NDIR CO₂ meters. Lastly, the color changing air quality status LED is a handy and reassuring feature.