The ultra-sensitive sensor of the YELLOW JACKET AccuProbe UV Handheld Leak Detector allows it to detect even the most difficult to detect R-134a R-404A R-407C R-410A and 1234yf refrigerants. Our exclusive solid electrolyte sensor technology reduces heat and gives the sensor longer life than traditional heated anode or heated diode detectors. The AccuProbe UV features low normal and high sensitivity levels with visual and audible signals and a 3 LED UV light system that works with 395-415nm wavelength leak tracing dyes. The audible alert which can also be muted and the flashing visual alarm indicator at the probe end increase in frequency and duration as concentration increases. The AccuProbe UV is equipped with the advanced digital SmartAlarm LED display. This feature takes the guesswork out of whether or not to repair a small leak. Unlike the more traditional LED bar graphs that copy or mimic the audio alarm signal the SmartAlarm digital leak size indicator measures registers and displays the leak size independently from both the audio alarm and sensitivity level on a scale of one to nine: Improved robust ergonomic design is easy to use in close areas and extendable into hard-to-reach areas Long life stable sensor Instantaneous response time Clears in 12 seconds or less after exposure to a 1.75 oz (50 g)/year leak Automatic calibration and reset to environment Low battery indicator Microcontroller technology SAE J2791 Certified CE Marked EN 14624 24-month limited warranty Made in the USA