Nu-Calgon - Fluorescent Gas Leak Detector is a complete product. Not only does it detect the smallest leak, it also provides other significant features and benefits. It's high viscosity formula enables it to remain in contact with the applied surface for an extended period of time, thereby allowing the smallest of leaks to be detected. Fluorescent Gas Leak Detector meets the technicians need for a quality, effective leak detector. It is non-corrosive to metal, which is a significant feature that helps to maintain the integrity of piping, tubing, and fittings. Being fluorescent-colored in order to facilitate visibility of bubbles in sunlight or bright lights, it is also freeze-protected and safe for use on all refrigerants, natural gas, and oxygen.