A maillon, maillon rapide or quick link is a metal link, similar to a carabiner. Maillons have a threaded sleeve which tightens over a thread, as opposed to a hinged gate like a carabiner, making them stronger, but more difficult to use. Like carabiners, maillons are available in a range of shapes and thicknesses (i.e. strengths), and often offer greater versatility over carabiners as their different shapes and lack of hinged gates allow them to be used in multi-directional load situations
This mallion is a square variation of the traditional quick link.