Collars are special large and elaborate ceremonial metal chains worn over the shoulders, hanging equally over the front and back, often tied with a bow at the shoulders, with a distinctive pendant attached to the front.
Collars are also worn when the King opens or prorogues Parliament, and for a few other observances, including religious services of the various orders, and by those taking part in the ceremony of introduction of a peer in the House of Lords.[1][2][4]