Artwork slightly different, but appears to be same product: “Using NDIR CO2 Sensor Technologies; Technical Specifications: CO2 Measurement Range: 0-3,000 ppm; Response Time: < 2 Minutes; Accuracy: 0-2,000 ppm ± 100 ppm or ± 7% of reading; Sensor Life Expectancy: 15 years”.
I'm not convinced this is truly the same product. A highly-rated review and some questions seem to say it does auto-zeroing and assumes the lowest concentration seen over some period of time is "outside", which as I understand it wouldn't be necessary if it were dual beam NDIR?
Not sure if they still make them with speakers that sound like life support monitors in the hospital, but if the beeping is too annoying you can just open the back and break off the speaker with pliers.
Artwork slightly different, but appears to be same product: “Using NDIR CO2 Sensor Technologies; Technical Specifications: CO2 Measurement Range: 0-3,000 ppm; Response Time: < 2 Minutes; Accuracy: 0-2,000 ppm ± 100 ppm or ± 7% of reading; Sensor Life Expectancy: 15 years”.