VW Bus wheel seal. The wheel seals mount on the back of the disc. They keep the wheel bearing inside the disc and keep the grease from leaking out and ruining your disc brakes. The wheel seal on your Bus should be replaced every time the disc is removed from the vehicle.
The wheel seals should be replaced anytime you remove the disc brakes from your VW Bus. During replacement you should inspect your wheel bearings and make sure they are still rotating freely. If not make sure to replace the inner and outer wheel bearings and repack them with a high quality grease to keeps your Bus rolling safely down the road. The discs that this seal matches up with are shown below.