An S hook is shaped like the letter S, with one curve holding each end of the chain, and it is common on harams and long necklaces where the length can be changed by moving the hook. Check that both curves are closed firmly enough to resist pulling, and that the thickness suits your chain. Press the ends gently to confirm they do not spread. Store a spare in a small box. Ask for the w... https://www.darjewellery.com/gold-jewellery/women/neckwear-accessories?f=subitem_name:S%20HOOK&sort=latest