Late to the party...again. Does no one put their rabies tags on collars anymore? I get at least one call a month asking to locate a found pet by our rabies tag. Our tags have our name, address and telephone number along with the tag number. I'm fairly certain that this is universial. Although I can't give the owner info to the caller - we relay info and make sure everyone is reunited. The S clips are much stronger than the O rings. I have lost some tags by mistakenly attaching leash to O ring, they are not that strong.