Gold or Silver Plated Pin Backing.
To use: Gently pull on both ends of pin backing to open it up and put it onto the pointy end of your pin. Let go of the far end, still holding the backing and your pin, and it’ll lock into place. Test by pulling on backing (also gently) to make sure it is secure. Use the same method to take off backing. (Disclaimer: Be careful when pulling the locked backing from your pin, make sure to unlock first and also don’t pull on it too hard)