The most traditional form of cufflinks – indeed, the original style of cufflink – is the chain link. These characteristically have two sides joined together by a few links of chain.
Because there is no rigid post to push through the shirt’s cuff holes, the chain link tends these days to be the preference of the expert-level cufflink connoisseur. A ball return – where the back end of the cufflink is a metal ball rather than a plate or disc – can overcome this problem to some extent, making it easier to manipulate the cufflink through the holes.
There are two big advantages to this style of cufflink. For one, there is something to look at on both sides of the cuff with a chain link fastening – the two sides of a chain link cufflink can both be decorative, typically as plates or disks with engraving, enamels, or simply the plain face of gold or silver. So they will appear as attractive from both sides of the cuff of your dress shirt.
In fact the chain link cufflink is effectively reversible, so that either side can be at the front.
By contrast, the back side or “return” on rigid-post cufflinks is often a utilitarian fastening like the bullet or whale back closure.
Chain link cufflinks typically allow for a looser cuff, too, which can feel freer on the wrist and allows the shirt to hang more naturally down the arm.