Help with oil tank cover

[fozzy2926]

My Xch is missing its oil tank cover. I'll be happier if I replace it but I don't know if I'll need the 'rubber element' as shown on the BMW parts diagram. On the diagram it looks like short length of tubing, not quite circular in section. I'm not going to bother with the spirit level so if the rubber element is just to do with that, that may be all I need to know. Does anyone know the answer?

Many thanks, Steve