Compass Refrigerant Leak Detector Provides The Optimal Balance Of Features, Function And Value. This Easy-To-Use Hand-Held Refrigerant Leak Detector Delivers Excellent Sensitivity To All Refrigerants, Up To 0.15 Oz/Year, Yet Resists Jobsite Contaminants Such As Dust, Dirt And Oil. Patented heated diode sensor provides excellent sensitivity High/Low sensitivity adjustment allows you to decrease sensitivity to pinpoint leak source Automatic background adjustment ("Zeroing") compensates for refrigerant build-up LEDs illuminate progressively to show leak size Runs on NIMH batteries or AC adapter Power indicator flashes when battery is low Water-resistant filter protects the sensor from moisture and contaminants Easy One-Button operation Headphone Jack (Headphones Sold Separately) 2-Year Over-The-Counter Replacement Warranty Made In The usa