Safety chain?

Hey! I'm working on my second Pandora bracelet and have about 20 charms. One of the bracelets I have has the threads on the ends, and one does not. I'm looking to get a safety chain, but the website doesn't really say what's it's for...I want it because it's cute and if it will protect my charms that's even better, but it looks as if the safety chain is only for the threaded bracelet? Can I get a safety chain for the bracelet that isn't threaded? Will it be a safety measure on the non-threaded bracelet or just decor? I'm pretty confused. Sorry if my terminology is wrong, I'll answer any questions in the comments. Thanks!!