This is a nice idea, it's really nicely made too, but it fails. Badly.
I'm not sure what its supposed to do to be honest...
Is it a chain so you don't need to unclip the hook to use the keys? If so the chain is too short and it fails.
Or is it simply designed to be unclipped every time you need to use it? If so the clip is too small for most belt loops, and it's fiddly. Fail.
A 2 inch longer chain and it would work, a bigger clip and it would work. At the moment an over engineered item that doesn't work.