---Easy-to-use formula: Fernox F4 Leak Sealer is designed for quick and hassle-free application. It comes as a ready-to-use liquid that doesn't require any additional mixing or preparation, making it convenient for homeowners and professionals alike. ---Effective sealing performance: This high-quality leak sealer is engineered to efficiently and reliably seal small, inaccessible leaks and weeping joints in hydronic heating systems. Its advanced formulation ensures a long-lasting and dependable sealing effect on various materials, including metal, plastic, and composite pipes. ---Compatible with all metals and materials: The versatile Fernox F4 Leak Sealer is suitable for use in systems containing a wide range of materials, such as copper, brass, steel, iron, aluminium, and plastics.