Klein Tools
Klein Tools ET110
$140
Klein Tools ET110 Overview
The Klein Tools ET110 is a mid-range CO2 monitor that tracks CO2, Temperature and Humidity. It uses a NDIR sensor — the technology we recommend for reliable CO2 readings — with a stated accuracy of ±75 ppm across a 0-5000 ppm measurement range. At $140, it is aimed at on-the-go monitoring, professional applications and HVAC integration.
In day-to-day use, the ET110 offers an onboard display, so you can read levels at a glance without opening an app, plus a portable design with 12 hours (3x AA) of battery life, making it practical to carry between rooms or when travelling.
Best For
Full Specifications
| Price | $140 |
| Sensors | CO2, Temperature, Humidity |
| Sensor Type | NDIR |
| Connectivity | |
| Display | Yes |
| Portable | Yes |
| Battery Life | 12 hours (3x AA) |
| CO2 Accuracy | ±75 ppm |
| CO2 Range | 0-5000 ppm |
Pros & Cons
Pros
- ✓True NDIR CO2 sensor (not an eCO2 estimate)
- ✓Built-in display for at-a-glance readings
Cons
- ✗No wireless connectivity for logging or alerts
Compare this monitor with others using our Monitor Comparison Tool
Frequently Asked Questions
Is the Klein Tools ET110 accurate?+
The Klein Tools ET110 uses a NDIR sensor with a stated accuracy of ±75 ppm over a range of 0-5000 ppm. NDIR is the proven reference technology for consumer CO2 monitoring.
What does the Klein Tools ET110 measure?+
It measures CO2, Temperature, Humidity. CO2 is the key metric for judging ventilation — levels below 800 ppm indicate well-ventilated air.
Does the Klein Tools ET110 need WiFi?+
No. The Klein Tools ET110 works standalone and shows readings on its built-in display.
Is the Klein Tools ET110 worth it in 2026?+
At $140, the Klein Tools ET110 is a solid choice for on-the-go monitoring, professional applications and HVAC integration. Its NDIR sensor puts it ahead of cheaper eCO2 estimators. Compare alternatives in our monitor comparison tool before buying.
How long does the Klein Tools ET110 battery last?+
The Klein Tools ET110 runs for 12 hours (3x AA), and its portable design makes it easy to move between rooms or take when travelling.