Hi Kev, It looks like the shroud that goes over the oil feed gause strainer at the rear, inside of the upper frame member. I can only guess that it stops air being sucked into the oil feed under heavy braking, where the oil may rush forward and leave the pickup exposed......not sure if there is a Vincent in existance that can stop that hard.....i'm sure most would agree that they seem to go better than they stop!!!Cheers for now.....Greg.