Cool Seal™ A/C Leak Sealer is a unique additive that seals slow, pesky leaks in compressors, condensers, evaporators, accumulators, O-rings and hoses ─ quickly and permanently. The non-polymer, oil-soluble formula is safe for A/C system components and recovery equipment and is compatible with all popular refrigerants, including R-1234yf (requires TP-9831CS adapter). Cool Seal is a practical alternative to expensive parts replacement on older, high-mileage vehicles and can remain safely in the system to guard against future leaks, making it ideal for preventive maintenance.