The ET120 is it the perfect choice for HVAC professionals. It is an easy-to-use tester that provides audible and visual alarms in the presence of methane, propane and other combustible gases at concentrations as low as 50 ppm. It features two levels of sensitivity depending on users' needs: High (approximately 50 to 1000 ppm) and Low (approximately 1,000 to 10,000 ppm). 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 isn't just the name of our company, it's also our family name. And since we're an American company that's family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesn't just make great products, we make great products that stand up to the demands of the professionals who use them every day ... Since 1857.