A straight rubber bypass hose from the water pump to cylinder head, 50mm length, as used in original applications. Trim to 42.5mm if you have a replacement 12a2075 bypass fitting in the head.
For installations where the head or tater pump have been removed. We recommend replacing this when the water pump or head gasket are changed, it is a cheap insurance. This is much stronger then the soft rubber collapsible hose designed for fitting while the head is still on the block.