Yellow Jacket 69339 AccuProbe UV - AU/NZ plug. Use the electrolyte sensor or UV technology (or both at the same time) to detect HFC, HCFC and HFO refrigerants, including SNAP approved hydrocarbon blends. The Smart Alarm LED shows how big or small a leak is on a scale of one to nine. With the electrolyte sensor, UV lights and Smart Alarm, indicator, this is the only tool you need for fast, easy and certain leak detection.