The Black & Decker thermal leak detector helps you increase the efficiency of your home's insulation by finding leaky areas that can lead to higher heating and cooling bills. You'll instantly identify problem areas around drafty windows and doors, and uncover hidden leaks and insulation "soft spots" around your home. Check windows, ducts, and walls with the thermal reference light that indicates hot and cold spots. You can even use the detector to diagnose engine misfires or check your refrigerator and freezer settings.