An ultraviolet dye that allows you to find leaks in an automotive air conditioning or refrigeration system. The dye is added to the refrigerant or antifreeze. Then, the underhood of the vehicle is shined with an ultraviolet lamp. If there is a leak in any area, it will be clearly visible under the UV light due to the bright dye. It comes in a bottle, and there is also a version in the form of 10 disposable syringes.