The answer is "a superfluous number".

To answer your coding question, Color #C0C0C0 is also called silver.

When my brother and I were toddlers ,he was only a year older than me and I hate to think how many patties she cleaned up every day. There was no such thing as disposible nappies in those days. He was a little runner so she sewed bells onto his shoes so then she always knew ehere he was.Pretty clever don't you think? LOL...in answer to your Q the tin bell will rust faster than the copper bell or the door bell.But the cow will still poo as much either way.

Cooper Cow Bells are not ment for everyday use, these are dress up bells and are worn for very special days only- I dare say this is another cow bell question and you must re-read your "Cow Bell" owners manuel for proper wearing, Thank you for your understanding.
GO COW BELL!