Every pendant arrives with its extender, because a chain that only fits one way only suits one neckline.
The pendant comes on a 16-inch chain. On most people that sits high, right at the collarbone, where the piece is fully visible above a crew neck or a shirt worn open.
In the box with it is a four-inch extender in the same finish, with a lobster clasp and four loops along its length. Clip the clasp to whichever loop you want and the chain runs from 16 inches to 20 in one-inch steps.
At 18 it sits just below the collarbone, which is where it lands most comfortably under a fine knit. At 20 it drops below a shirt collar, which is how a lot of people wear it to work — present, but only visible when they want it to be.
Nothing to buy separately, and nothing to send back for a resize.
We include it rather than selling it because a pendant that only fits one neckline is a pendant that gets worn less. And because sending a piece back to be lengthened is the sort of small friction that stops people buying at all.