RED TEK LeakStop, an a/c seal treatment from Thermofluid Technologies, is a formulated system designed to seal rubber parts and o-rings of air conditioning and refrigeration systems. LeakStop pressurizes and restores brittle o-rings that have been worn or damaged. Operation: Easy to use. Installs in minutes. Seals in seconds. Lower Cost: Less expensive than replacing leaking o-ring and rubber seals. Saves time and money. Compatibility: Compatible with most common refrigeration materials and lubricants including R134a, R12, metal components, mineral and synthetic(Ester and PAG) lubricants, seals, gaskets, hoses, compressors, and o-rings. Environment: Helps the environment by reducing refrigerant emissions. Safety: Safe and easy to use. LeakStop is less toxic than other seal treatments that contain poisonous methanol. IMPORTANT INFORMATION: This product cannot be returned because it uses flammable liquids and gases, is classified as a hazardous material, or meets other criteria.