Infrared Thermometers by Klein Tools. It has a wide measurement range of -4 to 752-Degree Fahrenheit (-20 to 400-Degree Celsius) and a 10:1 distance-to-spot ratio. The backlit display provides clear readings. 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. Klein isn't just the name of our company, it's also our family name.