Moderately priced, portable leak detector with proven heated-diode sensor technology. Tek-Mate Refrigerant Leak Detector, 0.40 oz/yr (11 g/yr) Sensitivity. Base unit includes sensor, 2 D-size alkaline batteries, spare filters, user manual, and storage case. The electrochemical heated- diode sensor resists dirt, water, oil, and other contaminants offering exceptional resistance to the effects of contamination. Features At A Glance: Equal sensitivity to CFCs, HCFCs, and HFCs eliminates resetting or switching for different refrigerants. Variable-intensity audible signal and single flashing LED to help pinpoint leaks. The automatic background compensation feature continuously monitors and automatically compensates for changing background "noise" without the need for manual adjustments by the operator. Two year warranty.