The ET110 CO Detector is an easy-to-use meter that detects and measures concentration levels of carbon monoxide (ppm) and temperature (Fahrenheit/Celsius), making it the perfect choice for HVAC professionals. Features backlit LCD screen, warning indicator light, audible and visual alarms and multiple function buttons. Includes carrying pouch and 4 x AAA batteries. For more than 160 years, Klein Tools has manufactured premium-quality, professional-grade hand tools that deliver the performance, durability and precision needed to get the job done right. Our family of engineers, workers and craftsman continue to put six generations of expertise into every tool we create by using only the highest quality materials, superior workmanship, and keeping manufacturing as close to home as we can. Klein isnt just the name of our company, its also our family name. And since were an American company thats family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesnt just make great products, we make great products that stand up to the demands of the professionals who use them every day ... Since 1857.