S11 - the NEW flagship
When it comes to size and bang for the bucks nothing compares to the carbon dioxide sensor S11. It's the size of a Wemos D1 Mini, powered over 3.3V or 5V, and supported by the biggest open source firmware projects out there. Get it from the source, First Byte is almost next door neighbours to the Senseair factory. We only sell quality assured sensors, you can't get that elsewhere!