I used these engraved metal tags for my two large dogs (now deceased) for over 10 years. They still look new after all that time. My dogs had the plastic buckle type of collar, and the tags never once moved a millimeter. I think it would have been really hard trying to get the slide on tags off if I wanted to change collars. I love the decorative tags for my tiny dogs, but I do like the ones on the collars too because they don't make noise, and they don't come off or get tangled on things.
You can have anything like chip numbers, rabies numbers, and phone numbers engraved on the tags so you can have one tag for everything.
Boomerang Tags