someone was asking about this and I dont remember who so I hope you see this its for the exhaust valves on the 900 as they do not stay open a wot and this will make sure they do, see pic you have to drill the two holes and add the seal and you need a dif bellows washer I think its from the 800 polairs the bellows part # 5132950 and the seal part #32431 its a prop shift seal for a boat motor.