While it's true that the Campagnolo O-Ring size is some weird metric size, the USA #204 size is very, very close to the Campagnolo size and virtually indistinguishable. On the CR mailing list two times in the past, someone has bought a pack of these O-rings (they cost about 2c each in quantities of 1000x), and distributed them to other CR list members for the cost of a self-addressed stamped envelope.
- Don Gillies
San Diego, CA, USA