Aranet4

• Dimensions: 2.80 × 2.80 × 0.94 in (71 × 71 × 24 mm)
• Weight: 3.7 oz (104 g) with batteries
• Sensors: CO2 (NDIR), temperature, relative humidity, atmospheric pressure
• CO2 range: 0–9999 ppm, ±(30 ppm + 3% of reading)
• Display: E-ink
• Battery: 2x AA, up to 4 years
• Connectivity: Bluetooth (Aranet Home app, up to 90 days of history)

Worth the price if you want an accurate CO2 monitor.

Tracking CO2 levels changed my life, and started traveling with this little gadget everywhere I go.