This seal is located near to the side flanges of the gear box on buses of Type 2  08/75-07/79 and Type 25 05/79-07/92. It prevents that the oil of the gear box leaks along the flanges/wheel driving shafts. After a long lasting leakage along the flanges damage can occur in the driving mechanism of the gear box due to a shortage of  gear box oil. From now on available each in German quality from stock.