- Modern Reproduction of the classic 2.5" butterfly filler cap, as used on Norton International and SOHC Manx oil tanks (as well as pushrod and sidevalve petrol tanks). This item is the same as 0120b except it is UK made and of a slightly higher quality than the other type. It comes supplied with rubber seal. I also sell cork style replacement washers (Item 0466) if you prefer to use that type.