INKBIRD IAM-T1 Smart Indoor Air Quality Monitor Portable CO2 Detector and Alert with Bluetooth App Monitor Temperature Relative Humidity and Air Pressure with Electronic Ink Display and 4 Years Battery Life

The size is just right, not too big. The change occurs every minute, but it can be adjusted to be slower to save battery. It's suitable for use in the car because it doesn't need to be plugged in for charging.

🔧 Durability: Uses 2 AA batteries, no need to worry about battery degradation.\n\n 👌 Ease of Use: Just insert the batteries and it's ready to go. There is a button to switch between °C/°F and to turn Bluetooth on and off at the back of the device.\n\n 📏 Accuracy: I haven't compared it with other devices yet, but from the reviews I've seen, it seems accurate enough for use. The sensor can be reset (calibrated). It comes with 2 batteries included, and if used to measure every 10 minutes, the battery can last up to 4 years.