Using the Klein ET110 Carbon Monoxide Detector is simple. First, insert the 4xAAA batteries that come with the device. Then, turn it on using the function buttons. You can use it to measure carbon monoxide levels and temperature in various settings, especially useful for HVAC work. Keep it in the area where you want to monitor carbon monoxide and temperature. When the detector senses high carbon monoxide levels, the warning indicator light will turn on, and you'll hear an audible alarm and see a visual alert. Make sure to keep the detector away from direct sunlight and extreme temperatures. To maintain it, regularly check the batteries and replace them when they're low. Also, clean the device with a soft, dry cloth. If you notice any issues, contact Klein Tools' customer service for assistance.