What does “Aftermarket” mean?

An aftermarket accessory is made by a third party to fit a particular brand's watches, rather than by the brand itself. Straps, bracelets, buckles, deployant clasps and storage boxes are the most common examples. Many are well made and perfectly reasonable to sell, as long as they are described honestly.

The key rule is wording. An aftermarket strap should be described as one that “fits” a model, never as if the brand made it. Using the brand's name as if it were the maker misleads buyers and can raise trademark issues. Buyers, in turn, should not expect aftermarket accessories to hold value the way genuine parts do, and should check quality points such as spring bars, buckle finish and how well the ends sit against the case. When a watch is sold on an aftermarket strap, the listing should say so, and ideally mention whether the original strap or bracelet is included.

A clear listing line: “Aftermarket rubber strap, fits Omega Seamaster 300M, 20 mm, black, not made by Omega.”