Hanging key rings like these are tough to find - even in a little hardware store
Oh, they are probably available, but searching them out - even in the key-making section, can be tiresome.
Each one measures 1 inch in diameter and is in the form a of split ring for easy key access. Some of the rings also have a few links of chain attached. Or, add your own chain, cord, leather or lanyard.
So, you can add a little doo-dad or charm easily for some extra pizzazz - or remove the attached chain (on some of them) easily by slipping it through the split ring.