Penrite Block & Cylinder Head Seal 250ML Block & Cylinder Head Seal is a permanent engine block, cylinder head and cooling system sealer formulated with ceramic fibres and copper to ensure a fast and permanent seal of gaskets, fractures and cracks in a vehicle’s cooling system.Block & Cylinder Head Seal is designed for use in all modern automotive cooling systems and is compatible with all types of materials used throughout the cooling system, including all metals, plastics and rubber components. It is compatible with all types of coolants and will not block the cooling system.Block & Cylinder Head Seal uses the latest ceramic fibre technology combined with copper to permanently seal broken and weeping head gaskets, block and cylinder head fractures, radiator cracks or splits and engine welch plugs to prevent coolant loss and engine overheating. It will also seal broken heater cores and prevent expensive coolant leakage that can cause damage to the inside of a vehicle.