AccuProbe II Leak DetectorThe YELLOW JACKET® ACCUPROBE™ UV and ACCUPROBE™ II Hand - held Leak Detectors detect all HCFC refrigerants such as R - 22 and R - 124. The ultra - sensitive long life sensor with exclusive Heated Electrochemical Sensor Technology (HES) also detects the more current, difficult - to - detect HFC refrigerants such as R - 134a, R - 404A, R - 407C and R - 410A (see page 6 for a more complete chart of detectable refrigerants). The ACCUPROBE UV is equipped with the unique digital SmartAlarm™ LED display - the first digital leak size indicator in a hand - held heated sensor leak detector. 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 the sensitivity level. The ACCUPROBE UV also features a 3 LED UV light system that works with 395 - 415nm wavelength leak tracing dyes. The sleek, ergonomic design of these YELLOW JACKET leak detectors makes them easy to use in close areas and extendable into hard - to - reach areas. When finding leaks, it is important to note that the AccuProbe responds to changes in concentration of refrigerant. For this reason, the detector will stop alarming even though it is held at or near the source of the leak and will not alarm again until the detector senses a change in concentration. To verify the exact location of the source of the leak, always move the probe away from the area of the leak briefly to allow the sensor to reset at a lower concentration, and then bring it back again until the exact location of the leak source has been verified. FeaturesAdvanced digital SmartAlarm™ leak size indicator (AccuProbe UV) Flashing visual alarm indicator at probe end (AccuProbe UV) Audio mute button (AccuProbe UV) Operates on 4 AA alkaline batteries (AccuProbe UV can also use AC power) 3 LED UV light system that works with 395 - 415nm wavelength leak tracing dyes (AccuProbe UV) Microcontroller technology Ultra - high sensitivity to detect 0.06 oz (1.7g)/yr. of R - 134a and 0.03 oz (0.9g)/yr. of R - 22 Automatic calibration and reset to ambient Detects HFC, HCFC and CFC refrigerants (see page 6) Long life stable sensor utilizing Heated Electrochemical Sensor (HES) technology 3 selectable sensitivity level settings Sleek ergonomic design Low battery indicator Temp Range 24° to 125°F ( - 4° to + 52°C) Humidity 0 to 95% RH noncondensing SAE J2791Certified CE Marked True mechanical pump.