A clasp according to embodiments of the present invention is particularly well suited to wrist bands of diving watches, specifically metallic link type wrist bands. Such a clasp can be worn in a first closed position during normal usage against a user's bare wrist. The same clasp can then extend so that the same watch and wrist band can be worn by a user over some additional material, such as a dive suit. The extension of the clasp is beneficial as it requires no tools, is simple and reliable.