According to the parts list on CMS, it's called "RING, BACK UP" and there should be one on each fork leg. Honda didn't fit something without a reason, play safe and get a new one where it's missing, CMS give the part number as 51412 446 003, and they are 5 euros each. Dave Silver hasn't got them in stock, but can get them to order, so chances are your local Honda dealer can get it for you, which saves postage!