Anchors aweigh. The mariner takes an oval link and lays a bar across the middle, which stops her twisting. The whole length stays face up all day without you touching it.

We bought her for that bar. It is what makes her read as one continuous line rather than a string of separate pieces, and it is why a seventies mariner still looks modern. At 2.3mm she has real presence at the collarbone. The lobster clasp is the one you can do up alone.