Water Pump Drive Shaft Seal AP0650315
Fitment - RSV 98-10, Tuono 02-10, Caponord 04-07
Genuine Aprilia water pump drive seal, part number AP0650315, item number 12 in the diagram.
This fits within the engine behind the water pump and seals the drive shaft preventing any oil from potentially entering the cooling system.
Please also see the water pump mechanical seal.