The revolutionary Fluorescence Leak Detector detects leaks by adding fluorescent dyes to air conditioning and refrigeration systems – without damaging the original refrigeration system. No extra equipment is required. The leak can be found after the system has been running for a while. Very small leaks can be enhanced with cumulative leak time. Once infused into the system, it will always be effective. It can be used permanently except for the fluorescent agent refill cartridge.